
The fire erupted in the early hours at section B of the isolated camp but the Hmong managed to flee their shelters, mostly bamboo huts. No casualties were reported.
"Our fellow Hmong, especially the children, are now in trouble as we lost our shelters last night and now the rains are coming," said a Hmong who could be reached by phone from the camp.
A Thai military official said the ethnic minority group from Laos simply wanted to create chaos to draw the attention of the international community, as United Nations Secretary-General Ban Ki-moon was in the region on a relief mission to Burma.
"We know they staged the incident because they moved their belongings out of the shelters prior to the fire," said the officer on condition of anonymity.
Officials on the ground will definitely arrest the arsonists and their leaders, he added.
Thailand now harbours some 8,000 Hmong from Laos who claim they are close associates of the United States Central Intelligence Agency's secret fighters against the Communist Pathet Lao movement before the fall of Vientiane in 1975.
They claim they have fled from suppression in their homeland, but Vientiane rejects the allegation and together with Thailand regard them as normal illegal migrants seeking better lives in Thailand, and perhaps resettlement in third countries.
Thailand has already repatriated hundreds of the Hmong since last year and will be sending more to Laos in the near future.
The repatriations were voluntary but some Hmong leaders don't want their people to go back and have threatened them, the military official said.