Burmese opposition groups say a recent offensive by the Burmese military government near its new capital in eastern Burma has driven thousands of people from their homes.
They made the announcement in Thailand as the opposition government in exile issued its annual report listing numerous human rights violations in the country.
The head of the Burmese Issues civic group, Saw Kweh Say, says the country's military government, known as the State Peace and Development Council, or SPDC, in recent months has attacked villages in eastern Burma.
"Since November 2005, the SPDC started a strong offensive close to the new capital called Pyinmana. And thousands of people crossed the border into Thailand and moved into refugee camps."
He says at least 4,000 homeless villagers are now camped in harsh conditions in Burma.
He made the announcement Wednesday as the National Coalition Government of the Union of Burma, an opposition government in exile based in the United States, presented its annual report on the country's human rights conditions.
A senior official of the coalition, Bo Hla Tint, says human rights violations in Burma continue unabated in all areas.
"Since the end of 2004, the incumbent regime is seemingly more inward-looking and more insecure. At the same time, they are becoming more hostile toward the democratic and ethnic forces."
He said that last year 144 political activists were detained, bringing the total number of political prisoners to more than 11,00. He added that 165 people, including women and children, were killed in extrajudicial executions.
The opposition leader called on the international community, especially the Association of Southeast Asian Nations - ASEAN - to press the Burmese government to begin a dialogue with opposition parties and ethnic groups.
The Burmese government says it is working toward political reform and has opened a national convention to draft a new constitution. However, critics say the convention has little meaning because the major opposition group is not participating.
An ASEAN special envoy, Malaysian Foreign Minister Syed Hamid Albar, visited Burma last week to demonstrate the group's concern over the lack of progress on political reform.
Syed said this week that his mission was incomplete because he was not allowed to meet opposition leaders, including pro-democracy icon Aung San Suu Kyi. But he also said the visit demonstrated that ASEAN was engaging Burma.
Former Thai ambassador to Burma, Asda Jayanama, says there is growing concern among Southeast Asian nations that Burma's problems are spreading across its borders.
"What goes on inside Burma affects us, ASEAN's image, intellectually, politically, but physically it affects Thailand in terms of workers coming to the country illegally, refugees, fighting on the border, amphetamine production and distribution in
Thailand and many other things."
The panelists agreed that ASEAN's influence on Burma, a fellow member, is limited. As a result, they said more powerful forces, such as India, China and the United Nations Security Council, must join in pressing for change.