Aug 26, 2009 (DVB), A mass exodus of Burmese into China has taken place this week following a standoff between Burmese troops and armed ethnic groups in northern Burma, local sources say.

An eye-witness in northern Burma's Namsan town told Reuters today that large groups crossed the border from Shan state's Kokang town into China on Tuesday. Around 10,000 people are thought to have crossed so far.

An alliance of four armed ethnic groups known as the Myanmar Peace and Democracy Front (MPDF) released a statement on 21 August detailing the standoff.

The statement, obtained by US Campaign for Burma, said that a "military confrontation" between the MPDF and Burmese army had occurred on 8 August "due to the military threat and instigation by the government with the reason of anti-narcotic action".

It added that the incident caused "shock and frustration" throughout the region and border area, and warned that it "effectively shadows and darkens" relations between ethnic groups and the government.

Relations between the Burmese government and ceasefire groups have been strained in recent months following pressure from the junta to transform themselves into border patrol groups.

The ruling State Peace and Development Council (SPDC) say the move would return groups to the 'legal fold', although a number of ceasefire groups claim it would significantly weaken them.

Furthermore, claims from the junta that the groups could form political parties to contest next year's elections have been dismissed as a ploy to neutralize their threat by bringing them under the government's control.

This year marks the twentieth anniversary of the first ceasefire agreements signed between the government and armed ethnic groups.

A number of significant groups, such as the Karen National Union (KNU), refuse to sign an agreement and continue to fight against the Burmese army.

The conflict between the KNU and government has stretched over 60 years, and is thought to be one of the world's longest running.

Reporting by Francis Wade