The result is a regime in which no one wants to pass bad news up through the chain of command, especially if it is serious enough to reach the top. And Cyclone Nargis - potentially the worst humanitarian crisis to hit the region in decades - has brought bad news in spades.

'There are officials we are dealing with lower down who are bright and flexible and know what needs to be done,' said one senior UN official based in Yangon who is in contact with government ministers to get foreign aid moving.

'But they are letting us know that there is a point where they can't or won't act ... some messages just can't be passed upwards, so crucial decisions cannot be made. It is a cancer in the bloodstream of the regime that has spread up and down, and the cyclone is showing us all just how serious the condition is.'

Another veteran Myanmese aid worker with close unofficial ties to ministers puts it in classical terms. 'Bad news cannot be tolerated and is a risk to anyone moving it up the chain ... and the end result is that Than Shwe risks falling into a trap of his own making. Than Shwe has modelled himself on the great Burmese kings, yet he is ignorant of the lessons of history ... he sits above a vast intelligence operation, yet he has divorced himself from reality.'

Describing him as 'God-King', Senior General Than Shwe's underlings live in constant fear, turning important planning sessions or action meetings into stilted, one-sided affairs, the aid worker said.

A brooding, heavy presence - he is known inside the regime as 'the Bulldog' - Senior General Than Shwe disdains small talk and doesn't like to be contradicted. He is also a master at playing less senior officials off against each other.

A humble postal worker turned career soldier, the young Than Shwe was schooled in psychological warfare during the long campaigns against Myanmar's restive ethnic minorities. A Myanmese traditionalist, he is wary of all outsiders, foreign envoys say, whether they are neighbouring allies such as China or India, or western governments.

Lower down the chain, such suspicions mean the decision-making process is swamp-like. 'Unless you can find a way of working quietly outside the system, you're doomed,' the Myanmese aid worker said. Unless Senior General Than Shwe is involved, it is very hard to achieve anything on a large scale.

It is into this climate of fear and suspicion that UN Secretary-General Ban Ki-moon must wade today. Arriving in Yangon last night, Mr Ban is due to take a litany of complaints directly to Senior General Than Shwe and plead for flexibility in the name of saving lives.

He will be the first foreign leader to meet General Than Shwe since Nargis hit nearly three weeks ago. Packing 190km/h winds, it pushed a wall of water more than three metres high deep into the delta, crushing all in its path, washing away entire stretches of coastline and the communities that lived on it.

The sense of urgency intensifies with each passing day. International Red Cross estimates put the death toll as high as 134,000 - a figure now thought to be rising as survivors struggle to find food, clean water and shelter. Mass outbreaks of diseases such as cholera and dengue fever are expected. Officially, however, the emergency is over, according to the regime.

Mr Ban faces an uphill battle as he seeks to seal a deal to allow regional aid workers to move the international aid piling up at Yangon airport and on French, British and US naval vessels lying in international waters just off Myanmar's coast.

The sour atmosphere of Senior General Than Shwe's meeting with Mr Ban's predecessor, Kofi Annan, in 2005 doesn't bode well. As soon as Mr Annan mentioned the continuing repression of opposition leader Aung San Suu Kyi - herself the daughter of revered general Aung San - Senior General Than Shwe ended the discussion early.

For most of the past few weeks, Senior General Than Shwe has been locked in self-imposed seclusion deep inside Naypyidaw, the gilded capital of his own design, 400km north of Yangon.

Over the weekend, he emerged to appear on state television - the only kind permitted - touring pristine refugee camps and aid centres.

The propaganda overlay was typically heavy as military-aligned newspaper New Light of Myanmar detailed his activities. 'Government takes prompt action to carry out relief and rehabilitation work,' read one banner headline on Tuesday - 18 days after the storm first hit.

Few are fooled. Frustration turns to rage as Myanmese and foreign aid workers talk of such images, given the harsh realities in the delta and around Yangon. The military response has been inadequate, with hundreds of thousands of people yet to be reached with food, clean water or medicine.

What many struggle with is the weak military response in the early days of the crisis. Myanmar's once proud army - now 400,000 strong - was the one asset the regime could call on. Together with planes, helicopters, ships and trucks - a mass mobilisation effort of the sort swiftly deployed in China - could have been mounted. Instead, the military appeared frozen.

A vast security apparatus of military intelligence officials and informers was instead on alert to keep unwanted foreigners - including senior UN officials - from the delta. The series of checkpoints also kept survivors trapped near their devastated land. The priority appeared not to be the storm, but a controversial vote on a referendum designed to ensure the continuation of 46 years of military rule.

'This I will never understand,' said one senior western diplomat this week. 'This regime has no interest in health care, serious economic management or education for its people. The one thing they have going for them - the military - acted far too slowly.

'We will never know for sure what happened ... but the best assessments I've seen have all pointed to the fact that the horrific news of just how bad the cyclone was sent the regime into a tailspin. No one wanted to go upstairs with the bad news to get the hard answers dealt with.'

The gap between reality and state propaganda was all too visible to this correspondent after slipping through military checkpoints on Sunday to reach the storm-battered town of Kyauktan, on the Yangon River southeast of the old capital.

A camp of blue tents designed as emergency shelters could be seen behind military barriers on the edge of town. Closer to the town centre, hundreds of homeless people huddled inside monasteries, schools and town halls, desperate for food, shelter and water.

Many had been turned away from the camp; others knew it was not even worth asking for help. Adding to their grief was the fact that local military officials demanded they return to their devastated land.

The situation is even worse in the hardest hit parts of the delta, where reports from aid workers describe mobs of starving refugees taking to the roads to head north in search of food. Children have been especially hard hit, with orphans arriving in refugee camps refusing to speak. They sit staring downwards with hands over their ears - a symptom of traumatic stress.

Above it all sits Senior General Than Shwe, chairman of the State Peace and Development Council. Aged 75, he has presided over the economic malaise that has made his resource-rich nation one of the poorest and most isolated in the region. Many of Myanmar's estimated 57 million citizens struggle to earn more than US$1 a day.

Little more than a decade ago, growth was a solid 7-8 per cent. Only a few years ago, former intelligence chief and prime minister Khin Nyunt was actively courting foreign investors with private sector reforms of Myanmar's hidebound socialist system. Overtures were also made to the embattled political opposition, victors in the 1990 election that was never honoured by the junta.

Now, however, Khin Nyunt and his relatively liberal cronies have been purged and Ms Suu Kyi remains in her University Road villa under house arrest. Growth has slumped, despite soaring oil revenues, and inflation is soaring.

Within the regime, Senior General Than Shwe is at the moment of his greatest power and dominance. Yet, with tragic irony, Cyclone Nargis has, for many, laid bare his weaknesses and vulnerabilities.