On December 15, the Royal Bhutan Army and Royal Bhutan Guards together launched Operation All Out to flush out an estimated 3,000 Indian guerillas holed up in the thick forests of the remote Himalayan kingdom, from where they have regularly staged hit-and-run strikes against Indian government targets in the rebellious northeast.

Buddhist Bhutan - wedged between China and India - shares a 380km unfenced border with the insurgency-wracked Indian states of Assam and West Bengal.

The rebels now fighting the military onslaught belong to three banned outfits: the United Liberation Front of Assam (ULFA), the National Democratic Front of Bodoland (NDFB) and the Kamtapur Liberation Organisation (KLO).

While the ULFA wants complete independence for oil- and tea-rich Assam, the NDFB and KLO are fighting for autonomous tribal homelands. Since the 1980s, rebel violence has killed more than 10,000 people.

Before the mid-December clampdown, guerillas gunned down Indian soldiers, bombed bridges and oil pipelines and abducted tea growers for ransom. They then escaped across the international border to their 30-odd training camps in Bhutanese territory, beyond the reach of Indian security forces.

Prime Minister Lyonpo Jigmi Thinley has announced that the crackdown - Bhutan's first military campaign since an 1865 war with the British - will not stop until the separatists are killed or expelled.

'We were left with no option after the expiry of a December 13 deadline to wind up camps and disappear. The rebels told us to tolerate their presence until they achieved their objectives, which meant that they would be in Bhutan for ever,' Mr Thinley said.

Bhutan claims that 6,000 troops are 'clearing the dense jungles inch-by-inch to eject the rebels, who are on the run'. But ULFA's self-styled commander-in-chief, Paresh Barua, insists that his forces are regrouping and hitting back.

ULFA chairman Arabinda Rajkhowa appealed to the Chinese leadership on Monday to give 'temporary asylum' to his men fighting the armies of 'India and Bhutan'.

Bhutan has so far given no casualty figures or allowed journalists access to battle zones. There are, however, reports of King Wangchuk, 48, leading from the front and Prince Jigyel Ugyen, the heir-apparent, sustaining injuries in action. The 19-year-old prince is said to have given up his studies at Oxford University and undergone two months' intensive training before enlisting without his parents' knowledge.

'It is impossible to verify claims and counter-claims,' said Wasbir Hussain, an Assam expert at New Delhi's Institute for Conflict Management. 'The final outcome will be known in a couple of weeks.'

The Indian Army, which candidly admits overseeing the Bhutanese operation, said 150 rebels and 10 Bhutanese soldiers had been killed in two weeks of fighting. Moreover, about 250 rebels fleeing Bhutan have been captured by Indian troops at the border. Among weapons recovered from overrun rebel bases are as many as 500 assault rifles, 328 small arms, rocket launchers, mortars and anti-aircraft guns.

Indian involvement is no secret: the first announcement of the crackdown was made not in Thimpu, Bhutan's capital, but on the floor of India's Parliament by Foreign Minister Yashwant Sinha. Mr Sinha publicly said that the king of Bhutan spoke to Prime Minister Atal Behari Vajpayee, who gave the go-ahead.

New Delhi admits that it is providing logistical support, medical services and ammunition, but flatly denies reports of Indian army soldiers fighting alongside the Bhutanese.

Much to India's embarrassment, however, the Hindustan Times reported on December 23 that 17 Indian soldiers died fighting in Bhutan in the initial stages of the crackdown, and their bodies were flown to the army's divisional headquarters at Bingauri in Bengal for burial.

Tiny Bhutan, with a population of 2.2 million spread over 47,000 square kilometres, is solely dependent on India for development funds and defence requirements.

As fighting raged, Bhutan suspended national carrier Druk Air's flights between Thimpu and Dhaka, the capital of Bangladesh, where India claims many middle- and top-ranking leaders of ULFA, the NDFB and KLO are hiding.

Mr Vajpayee's government accuses Bangladesh not only of harbouring some of India's most wanted rebels, but also of allowing Pakistan's Inter Services Intelligence to set up bases, allegedly to launch subversive operations into eastern India. Bangladesh vehemently denies the charges.

Last year, New Delhi handed Dhaka a list of 99 militant training camps allegedly operating from inside Bangladesh and demanded that it round up 77 insurgents from India's northeast and repatriate Indian rebel leaders jailed in Dhaka.

When Bangladesh denied the existence of any such camps on its soil, New Delhi claimed it had satellite pictures and the exact locations of the camps.

India now wants Bangladesh to take a leaf out of Bhutan's book. Hardline Deputy Prime Minister Lal Krishna Advani said India would cite Bhutan's 'shining example' at the next meeting of [India's] Border Security Force and the Bangladesh Rifles on January 6 and urge Dhaka to destroy militants' camps.

But Bangladesh's Foreign Minister, Morshed Khan, has rejected Indian calls.