A two-year-old girl has died and seven others remain missing after a mudslide at a refugee camp in northern Thailand near the Myanmar border, police said Monday.

The camp in Mae Hong Son province is home to around 10,000 people from Myanmar's ethnic Karen group, forced to flee a conflict that has festered for decades between rebels and the military.

Heavy monsoon rains in the mountains surrounding Mae La Oon camp caused the disaster late on Sunday, Thai Police Colonel Kantapat Netipitchayapong said.

"The authorities are still looking for the seven missing," he told AFP, adding that the mudslide wiped out 12 houses.

"There are 11 people with minor injuries and a two-year-old girl died," he said.

Mae La Oon is just three kilometres from the Thai-Myanmar border, one of the most remote of the numerous refugee camps lining the jungle-covered frontier.

Many families have lived in the border camps for decades, victims of a civil war that has rumbled on since Myanmar gained independence from colonial power Britain.

The Karen National Union has officially signed a peace deal with Myanmar's government but its armed wing is still locked in what is one of the world's longest-running civil wars.

But the insurgency has often been forgotten by the outside world and has in recent years been eclipsed by the Rohingya crisis on the other side of the country.

Myanmar's leader Aung San Suu Kyi, has made it a priority to bring peace to the country's restive border areas and has pressed rebel groups to join a faltering ceasefire accord.

Two more groups signed up earlier this year but fighting continues in many areas where the ceasefire is supposed to be in effect, while other rebel groups refuse to participate.

Thailand is expected to face three more days of heavy rain as the tail of deadly Typhoon Mangkhut whips the country, after killing scores in the Philippines and causing widespread havoc in Hong Kong and China.

© AFP