Nick Meo travels to the Thai-Myanmese border to meet the ethnic Shan soldiers fighting Yangon for independence

With a phalanx of orange-robed monks seated behind him and a battalion of peasant soldiers in front, Colonel Yawd Serk rose to address his people in their mountain-top fortress on Myanmar's side of the border with Thailand.

The man they call "the leader" congratulated his rebel warriors on surviving their 49th year of war and pledged to fight on against the brutal generals in Yangon until the Shan people taste victory and freedom.

Rows of well-drilled men in uniforms cast off by the Cambodian army listened intently, the Shan State Army's snarling tiger symbol stitched on to their jacket shoulders and an extraordinary range of weaponry in their hands: M-16s and grenade launchers from the Vietnam war, AK-47s, Uzis and ancient Bren guns made in Britain.

From their primitive base of thatched huts at Doi Tailang, perched on a ridge with spectacular views of mountains in Thailand in one direction and jungles in Myanmar on the other, the colonel's army is one of the few ethnic rebel forces opposed to the ruling junta to still put up much of a fight.

For foreigners the base can be reached only from the Thai side by clinging to the back of a motorcycle for four hours on a forest logging trail, before dismounting to walk around Thai border posts.

Until a decade ago, the Shan were key players in the Golden Triangle and controlled a huge swathe of territory under the leadership of Khun Sa, once the world's most powerful opium warlord. But in 1996, the warlord switched sides to join the junta in return for a cosy retirement, leaving his mercenary army to surrender, die or fight on.

The soldiers of the Shan State Army are the ones who refused to surrender.

Now they control just a slither of land along the Thai border, are bereft of income from the opium trade, which they have renounced, and lack international support. But they remain determined to liberate their homeland.

"Colonel" Yawd Serk, once a lieutenant of Khun Sa, claims to wage war on the drugs trade, which he believes has brought nothing but misery for the Shan. Their struggle has triggered a brutal mass relocation campaign of more than 300,000 Shan civilians. Risking being shot on sight if they return to their old villages, tens of thousands of displaced villagers have escaped to Thailand. His soldiers love him. They are a mix of teenage boys and gnarled old veterans, unpaid volunteers who cover their torsos with mystical tattoos for protection against bullets and the evil spells of their enemies. Many have had arms or legs blown off by mortars or landmines.

The colonel joined them at celebrations for the Shan New Year last week, dancing with his people and toasting freedom with rice wine as paper balloons fuelled by candles were released into the night sky.

Sai Yon, a 19-year-old private with a toothy grin, said: "The colonel is a good leader. He is trying to get our country back."

The clerics support him with equal enthusiasm. The Venerable U Thama, the abbot of Doi Tailang's Buddhist temple, said: "If it wasn't for Yawd Serk us monks couldn't be here."

The junta hates him. The Shan State Army claims to have killed 200 government soldiers in daily attacks inside the state in the last year.

A few kilometres from Doi Tailang is a first world war-style frontline with barbed wire and machine gun emplacements overlooking positions at the bottom of the mountain held by the Wa, former headhunters once known as the Wild Wa and now allied to the regime.

They have been promised Shan territory if they can overrun Doi Tailang and tried to earlier this year in a vicious battle in which 300 of their men died in attacks launched after they consumed amphetamines for courage.

Yee Tip, a Shan politician, said: "The British taught the Burmese well about divide and rule. Now they turn one people against another."

Three times, assassins sent by the junta have tried to kill the colonel on his frequent trips to Thailand, where his family lives. He refused to reveal what happened to his would-be killers but said darkly: "If someone tries to kill you, you are justified in killing them first."

Everywhere he goes he is trailed by bodyguards with Kalashnikovs and his assistant, a former monk with the nom de guerre of Philip, who swapped his prayer beads and robes for a sidearm when he joined the Shan's armed struggle.

Philip said: "We will take back Shan state one day. We just don't know when that will be."

The regime they fight is an international outcast notorious for its brutality. It attacks villages in Shan state where the Shan army and other rebels are active, and it is accused by the Shan of killing relatives of any Shan army members its military intelligence can track down.

Colonel Yawd Serk, who at 49 is as old as his people's war, said peace can only come when the regime gives rights and self-government, or an independent state, to the Shan people and withdraws from the drugs trade.

He claims to attack heroin factories run by the military and opium mule trains, and insists he tries to stop villagers from growing the plant.

Foreign help is non-existent, he claims, although the US Drug Enforcement Administration sends occasional observers to Doi Tailang on quiet intelligence missions.

Colonel Yawd Serk said: "It leaves a bad feeling that the international community won't help. Why can't they understand us? If we were making money out of opium we would be much better armed than we are now and the Thais wouldn't tolerate us on their border. These days all the Shan agree that Khun Sa's way was wrong."

Soldiers caught smoking opium are jailed. Execution is the penalty for a third offence, which the colonel says has never been carried out.

How the Shan State Army is financed is a mystery. "Taxes" is the official answer.