In an obscure part of southwest China, a refugee crisis from one of the world's longest running and least known conflicts in Myanmar is slowly unfolding, largely ignored by the outside world and denied by China.

Thousands of refugees bringing tales of rape and violence have flooded across the border into China, fleeing fighting between Myanmar government troops and ethnic minority Kachin rebels.

Conflicts between the Myanmar government and various minority rebel groups erupted soon after independence from Britain in 1948.

The Myanmar government is keen to end the violence as it introduces democratic reforms after five decades of iron-fisted military rule and as Western governments call for peace as they prepare to lift sanctions.

Concrete moves to end the conflicts is a condition for the full lifting of the embargoes.

While pacts have ended the fighting in most parts of Myanmar, the bloodshed has not stopped in Kachin state in the far north despite a call from the central government for an end.

Kachin state, a broad spur of Himalayan foothills wedged between China and India, has for generations produced some of the world's finest jade, as well as opium and timber.

Now it is central to the energy plans of both Myanmar and China, home to hydropower dams and twin pipelines that will transport oil and natural gas to China's southwestern Yunnan province.

In the town of Nongdao in a far western nook of Yunnan, talk of Myanmar's return to democracy and the release of political prisoners ordered by President Thein Sein rings hollow to refugees such as Da Shi Jar Raw.

They used big rockets to hit the villages and they burned the fields, the 32-year-old told Reuters, describing attacks by government soldiers in the country also known as Burma.

The Burmese soldiers are raping women and shooting children, she said. They killed a lot of mothers so we don't dare go back.

TERRIBLE THINGS

Labang Roi Tawng took her four young children and fled on a four-day trek in December to the border and safety at a camp in China of more than 500 people.

The military were killing, shooting and raping people, doing terrible things, so we were very afraid and ran, she said.

At least 10,000 refugees have entered China since fighting erupted between Myanmar's military and the Kachin Independence Army (KIA) after a 17-year-old ceasefire broke down last June. Some Chinese media reports have put the number at 40,000.

How long the fighting continues, we cannot say, said Lahpai Zaulat, with the Kachin Relief and Development Committee at Longdao, another area where refugees have flocked.

More and more will come, he said of the flow of people fleeing, adding new huts were being built every week.

At one camp, where a mass of huts nestled between an open rubbish heap and farmland, organisers said refugees were arriving at a rate of about 10 a day.

Most of the Kachin villagers have fled to several areas along the fenceless border including Mai Jai Yang in Kachin state, and Nongdao, Longchuan and Leiji on the Chinese side.

The flow of displaced appears to be under control for now, with authorities grudgingly providing land for shelters.

Many refugees in two border camps visited by Reuters looked relatively healthy and well fed despite often dirty and crowded conditions in huts of plastic tarpaulin strung over bamboo.

But what baffles many Kachin is that President Thein Sein's order for troops to end their offensives has fallen on deaf ears. The only explanation the government has provided is problems with communications equipment.

But few are convinced by that.

The military has ignored government orders to stop fighting, Khon Ja, a Kachin activist based in Myanmar's commercial capital of Yangon, told Reuters.

This should be the highest crime.

Channels for dialogue with the KIA are open and talks are going on, but without any real progress.

BORDER PEOPLE

For its part, China, keen to secure Myanmar's energy supplies and wary of an influx of displaced, officially denies the existence of the refugees. They are an embarrassment to a government which enjoys close ties with Myanmar and has stood by it in the face of Western sanctions.

Remember these people aren't refugees, they're just here temporarily to escape the conflict, said a Chinese government official in the border town of Ruili after police detained a Reuters news team for nearly five hours.

Chinese Foreign Ministry spokesman Liu Weimin, speaking at a briefing on Friday, described the refugees as border people and said there were not as many of them as outside reports say.

China has all along dealt with this issue in a humanitarian way, and has provided daily necessities, he said.

China has been relatively tolerant in allowing the Kachin to stay, many without identity papers, sometimes in border towns among Chinese citizens who share the same ethnicity. But it is wary of allowing non-government organisations (NGOs) to help.

The NGOs can't come to help us because China doesn't have any refugee laws, said refugee Joseph Dabang. Really we have tremendous trouble and we have no money.

Many Kachin are Christian and Christian organisations are helping to run camps and supply rations.

In another camp, that spilt into a plantation, corrugated iron shacks were crammed with bedding and scores of children gathered at a school set up with plastic sheeting for walls.

Teacher Htu Raw darted between blackboards as she taught two classes at the same time, getting children to recite English words like flower and cup.

I'm very sorry for the children so it doesn't matter if I'm tired, said the round-faced teacher as a room full of wide-eyed children watched her every move.

Many of these children have lost parents. But these students are now my children.

(Additional reporting by Maxim Duncan in Nongdao and Ben Blanchard and Sabrina Mao in Beijing; Editing by Martin Petty and Robert Birsel)