On the jungle border between Thailand and Burma, tens of thousands of refugees belonging to the ethnic Karen minority are nervously awaiting another dry season offensive by the Burmese army.

SImon Ingram reports from Burma where the army has razed villages to the ground

It is 50 years since leaders of the Karen took up arms against the government in Rangoon to press their demands for a homeland of their own.

The forces of the Karen National Union have suffered serious military setbacks in recent years, but the nationalist struggle - one the world has often overlooked - shows no sign of exhaustion.

Entering the real Burma

There is a drought looming in the forested hills that line Thailand's western border.

The rice paddies are cracked and parched. Most of the teak saplings have lost their leaves. So meagre were the rains that fell here in what should have been the wet season that the river Moie, dividing Thai from Burmese territory, has slowed to a sedate trickle.

Entering Burma by crossing the river may be an unorthodox route, but the authorities in Rangoon leave foreign journalists with little choice.

The few reporters allowed into the country do so under strict conditions that would certainly preclude access to the border areas we were hoping to learn more about.

At the top of the river bank we found an encampment of fragile bamboos hacks where about 4,000 people had settled, and more were arriving all the time.

Homes razed to the ground

These people had brought next to nothing with them, so hastily had they fled their home villages. An old woman described how her family had heard shooting in the woods beside their home, and realised that army troops were closing in.

The displaced Karen ethnic minority find their villages burned to the ground

We gathered up the children and ran, she said. Next morning, one of the men ventured back to see what had become of the village. He found it had been razed to the ground.

The scorched-earth tactics of the Burmese army against the various ethnic minorities living in the east of the country are nothing new. But this year, there is compelling evidence that the campaign against the 7 million Karens is being waged with particular viciousness.

Village after village is burned down, crops and livestock are destroyed or stolen. Those people who do not escape are used as forced labour, or made to serve as human mine detectors, walking in front of the advancing Burmese troops.

Stories of rape are becoming increasingly common. The chilling phrase "ethnic cleansing" is one that human rights monitors based along the border are using with growing regularity.

Kevin Heppner of the Karen Human Rights Group says: "They just can't survive any more. They can't work their fields any more and they're also terrified of being shot on sight in their fields which often happens, or shot for fleeing forced labour, so they have no choice but to run."

Rangoon losing its grip

In spite of its annual offensives, Rangoon's grip over the Karen border regions is less than total.

The Karen National Liberation Army claims its guerilla tactics are working well

The rebel forces of the Karen National Union have lost most of their territory, but senior officers claim their guerrilla tactics are inflicting significant and regular losses on the Burmese troops.

But the claim is hard to verify in a conflict which splutters on virtually unnoticed by the outside world, and whose very existence the Burmese authorities routinely deny.

On the evening of my visit to the riverside refugee camp, the news on Myanmar (Burmese) television showed a uniformed and smiling official bearing the sinister title of Secretary Number One being greeted by respectful residents of some provincial town.

The ruling State Peace and Development Council likes to talk about its drive to achieve national reconciliation - but nothing that could ever be construed as ethnic cleansing.

British debt to the Karen people

In a remote jungle clearing, we waited under the watchful eye of several Karen fighters carrying M16 rifles for our meeting with the KNU's veteran president, Bo Mya.

Symbolically he had chosen to meet us inside Burmese - or as he would have it - Karen territory.

The general looked tired - as well he might. For 20 years, he has led his people's armed struggle against Rangoon.

He had 12,000 men under his command, he said, ready to fight and die for the cause. You British should be doing more to help us, he added, with an accusing glance.

The Karen people sided with Britain against the Japanese in WWII, he went on. But you forgot our sacrifice and handed power to the Burmans in Rangoon.

What the Karen see as the betrayal they suffered at the hands of Burma's former colonial masters has become a persistent stain on the national consciousness.

In the crowded refugee camps inside Thailand - themselves the target of armed attacks over the years - a different, more hopeful consciousness flourishes.

The camp elders produced a troupe of children in white national costumes to perform traditional Karen dances for us. As I watched their graceful movements, it occurred to me that many of the dancers probably knew nothing except a life in exile.