Successive Thai governments - military, democratic or autocratic - have courted both giants in a hedging strategy so striking that both China and the US now count Thailand as their most important friend in Southeast Asia. It will be intriguing to see how any Sino-US rivalry over Thailand plays out in coming years. Thailand's political turmoil and questions over the royal succession add to the uncertainty.

Thaksin - who is on the run from a two-year jail sentence - aborted a plan to appear two weeks ago at the Foreign Correspondents' Club in Hong Kong; instead he spoke, slightly distorted, three days ago on a grey-tinged screen via a hastily arranged video link from Dubai.

'I have had no conversations with the Chinese or Hong Kong governments, but I have some kind of feeling that they may be uncomfortable because of their relationship [with Thailand],' he told a packed audience of businesspeople, academics and journalists. 'So I'd better stay away to protect that relationship.'

Thaksin was the most popular and the most powerful elected prime minister Thailand has known. During his five years in power, he pushed the nation even closer to Beijing.

He also pushed through a deal on a free-trade pact with minimal oversight, and pleased mainland leaders by making life harder for Falun Gong and Taiwanese elements in Bangkok - even though he courted domestic controversy by doing so.

He kept the US happy as well, allowing the CIA to run so-called 'black' flights through Thailand carrying terror suspects in the wake of the September 11 attacks - though Thailand denied any of the suspects were held on its soil. This smoothed the way for the country to be declared a 'major non-Nato ally' of Washington in 2003.

Beijing found in Thaksin, a first-generation Thai Chinese, a warm partner to deal with. But it was playing a long game, and had established more enduring contacts in the political establishment, and in business and royal circles, whose members had always been suspicious of the billionaire telecoms tycoon.

China was the first major power to recognise Thailand's military-led government after the ousting of Thaksin in a bloodless coup in 2006.

Thaksin appears to know he is damaged goods as he runs short of money, time and options in the wake of his conviction in absentia in October for abuse of power in a land deal while he was in office. Beijing does not seem ready to sacrifice the connections it has built up in Thailand for the sake of a former leader in Thaksin's position.

Diplomatic and political analysts believe that while China would be reluctant to get involved overtly by extraditing Thaksin to Thailand, it wants him to keep a low profile while on Chinese soil.

Zhang Yunling, of the Chinese Academy of Social Sciences' Institute of Asia-Pacific Studies in Beijing, said China would uphold the principle of non-interference and keep out of whatever decisions Thai authorities made regarding Thaksin.

Professor Zhang said Beijing attached high importance to relations with its neighbours, and relationships with those in power were especially important no matter how close Beijing was to Thaksin when he was in power.

Those relationships have been in play for decades, partly because Thailand has assimilated overseas Chinese to a far greater degree than any other country in the region. At least 60 per cent of Bangkok residents consider themselves to have Chinese blood.

While China surprised many international analysts with its swift donation of more than US$1 billion to the bailout of Thailand led by the International Monetary Fund at the height of the regional financial crisis in 1997, that action was merely a reflection of a trend that went back more than 20 years.

Ian Storey, a fellow at Singapore's Institute of Southeast Asian Studies, has noted how China sold Thailand oil at so-called friendship prices during the oil shock of the early 1970s, and formalised diplomatic relations in 1975.

'There is a comfort level that has only continued to grow,' Dr Storey said. 'China sees the Thailand friendship as a special relationship - and easily its most important in Southeast Asia - and that is not easily affected by whoever is in power.'

Vietnam's invasion of Cambodia 30 years ago - as cold-war tensions roiled communist neighbours - pushed the armed forces of Thailand and China into a relationship of convenience, as they worked to help the ousted Khmer Rouge in their jungle hideouts. Those links have blossomed into a strategic relationship that has seen the two militaries embark on joint exercises in recent years and Thailand buy Chinese weapons and ammunition. Thai officers have also undergone training in China, and the two sides now hold annual defence talks.

Dr Storey said the relationship was not all smooth sailing, with evidence pointing to unhappiness among Thai military brass at the quality of both Chinese materiel and training. 'The relationship is highly significant but it is dwarfed by the depth and scale of the US-Thai military relationship. That is America's strongest and most historic military relationship in Southeast Asia. I can't see China matching that any time soon.'

China's emerging military relationship with Thailand was acknowledged in July as both countries toasted the 33rd anniversary of formal ties during a visit to Beijing by the Thai prime minister at the time, Thaksin crony Samak Sundaravej. Speaking in the Great Hall of the People, President Hu Jintao said China and Thailand were 'each other's good neighbour, brother and partner, with the two peoples sharing deep traditional friendship'.

Noting that the relationship had 'always been ahead' of ties with its other neighbours in the region, Mr Hu added: 'China greatly appreciates the way ... King Bhumibol [Adulyadej] and the Thai royal court and government give priority in developing Chinese ties ... and thanks Thailand for giving valuable support on such major issues as Taiwan, Tibet and the Beijing Olympics.'

Mr Hu's reference to the Thai royalty served as a reminder of Beijing's close ties with Crown Princess Sirindhorn, the king's popular second daughter.

Thitinan Pongsudhirak, director of the Institute of Security and International Relations at Bangkok's Chulalongkorn University, said China was now the most connected major power in Thailand in 'ways we don't see'.

'It has strong links across the political and royal spectrum ... The US is always first and foremost, but the trend towards China is there. You give it 20 years and they will be even,' he said.

Dr Thitinan sees China's rising connections as a combination of accident and design rather than a grand, conspiratorial competition.

One factor to watch in coming years would be Thailand's troubled democratic development, he said. 'If Thailand becomes less democratic, it will find the Chinese development model more appealing ... and that could further China's influence.'

Western and Asian diplomats say they can see a time when, for all Thailand's hedging, it leans even closer to China at the expense of the US.

'It won't necessarily be marked or striking, but it could prove to be a significant tilt - and that will be something Washington finds hard to live with,' a veteran western envoy said. 'Some of us are already talking about it like the new 'Great Game'.'

Few expect it to happen suddenly. Instead it will be gradual, given the enduring strength and depth of US ties - even though those aspects may not always be obvious.

Fearful of anti-royalist communism taking hold, Thailand played a key role in helping the US project its military power during the Vietnam war, welcoming planes, troops and supply bases.

In the process, the military, FBI and CIA developed key Thai institutions and trained thousands of personnel - far beyond anything else attempted in the region.

In the 1950s and 1960s, the CIA even played a role in helping to fund and organise efforts to promote support for King Bhumibol, whose moral stature is now unquestioned in Thailand after 62 years on the throne. Such links remain valuable today.

Both China and the US maintain extensive intelligence operations in Bangkok as part of their diplomatic presence. Both sides court prominent and 'useful' Thais of all political shades.

As he spoke to the FCC on Thursday, Thaksin appeared to be placing a dollar bet each way, aware that his comments would be heard in both Washington and Beijing - which are both still issuing him visas. He questioned the excesses of Wall Street capitalism and Washington's faith in free markets, yet praised democracy.

As a former prime minister, Thaksin knows better than most the increasing complexity and importance of Thailand's relations with both countries.

Additional reporting by Kristine Kwok