Aizawl/Agartala, Nov 15 : Mobs have set fire to over 225 huts of Reang tribals in Mizoram, displacing several thousand people as tension escalated following the gunning down of a Mizo youth, officials said here Sunday.

"The mobs have set ablaze more than 225 houses of Reang tribals in seven villages under Mamit and Kolashib districts in southern Mizoram since Saturday, displacing over 5,000 people," a Mizoram home department official said.

The displaced tribals have taken shelter in adjacent south Highlakhandhi areas of southern Assam and Jampui in northern Tripura.

"The ethnic violence erupted after the militants shot dead an 18-year-old Mizo youth at Bungthuam village, near the Tripura border, in southern Mizoram on Friday," the official told reporters.

The youth was shot dead when he and his friends were collecting pig fodder in a forest area. The two gunmen fled the spot soon after the incident.

A little known militant outfit - Bru National Army (BNA) - claimed responsibility for the gunning down of the youth.

Condemning the killing, several political parties and the influential Young Mizo Association (YMA) in separate statements have demanded that those behind the killing be arrested and punished.

Warning the troublemakers, Mizoram Home minister R. Lalzirliana said those who disrupt peace would be firmly dealt with and brought to book.

District authorities in southern Assam and northern Tripura held meetings with local leaders and Reang tribals to maintain peace in the mixed populated areas.

"Both civil and police administrations in northern Tripura are on alert to prevent any eventuality following the ethnic violence and exodus of Reang tribals from Mizoram," said north Tripura district magistrate Samarjit Bhowmik.

"Senior civil and police officials since Saturday have been camping in the villages adjacent to Mizoram," Bhowmik told IANS by phone.

Over 35,000 Reang (locally called Bru) tribal refugees have been living in six north Tripura camps since 1997 after they fled Mizoram following ethnic clashes with the majority Mizos.

The tripartite meeting held in Aizawl Nov 4 between representatives of the central and Mizoram governments and tribal refugees failed to resolve the 12-year deadlock to repatriate 35,000 Reang migrants from Tripura to Mizoram.

"Both the centre and the Mizoram government rejected our major demands. We will not return to our homes unless our vital demands are fulfilled," said Elvis Chorkhy, who led the seven- member refugee delegation at the meeting.

"We will boycott the repatriation process as both the Mizoram government and the centre are not sincere about conceding our long pending demands."

Mizoram Bru Displaced People's Forum (MBDPF), a body of the Reang tribal refugees, has sent fax messages to Prime Minister Manmohan Singh, United Progressive Alliance (UPA) chairperson Sonia Gandhi, Home Minister P. Chidambaram and Mizoram Chief Minister Lalthanhawla, urging them to stop the ethnic violence in Mizoram.

"The tribal refugees Sunday organised protest rallies in their six camps in north Tripura to protest the mob attacks and burning down of houses belonging to Reang tribals in Mizoram," said Chorkhy, who is the president of MBDPF.