BOSTON - Burma's junta held nearly 1,200 political prisoners before a crackdown on Buddhist monk-led street protests last month, according to a report by the U.N.'s independent expert on human rights in Burma.

The report, which U.N. special rapporteur Paulo Sergio Pinheiro plans to deliver to the United Nations next week, showed the number of political prisoners rose from at least 1,100 in 2005 to 1,192 as of July 27 this year.

Describing a "culture of impunity prevailing in Burma," the 19-page report painted a picture of widespread abuses -- from arbitrary arrests to seized land, harsh prison conditions and forced labor -- before the regime's brutal crackdown on pro-democracy protesters.

"The special rapporteur has received many allegations of villagers being severely punished because they refused to perform forced labor," said the report, a copy of which was obtained by Reuters.

In an e-mail to Reuters on Friday, Pinheiro said the report was completed in August and sent weeks ago to the United Nations because of the need to translate and edit the document in six languages before his U.N. presentation next Wednesday.

It comes as U.S. President George W. Bush plans to announce further sanctions against Burma's military rulers.

Between Jan. 12 and July 31, Burma's leaders arbitrarily seized property and assets, and forced people to relocate across the country, especially from areas where ethnic Karen rebels dwell in the rugged mountains along Burma's eastern border with Thailand, the report said.

IMPOVERISHED VILLAGERS

It estimated 540,000 people have been displaced in eastern Burma with "minimal" prospects of being returned and resettled. As of July 9, there were 139,075 refugees from Burma living in Thailand, it said.

"Military operations in rural areas have contributed to the impoverishment of villagers," he said in the report.

Pinheiro, a Geneva-based Brazilian law professor who reports to the U.N. Human Rights Council, has visited Burma six times since he was asked to keep an eye on its human rights performance in 2000.

Pinheiro has not been allowed back since November 2003 despite repeated requests. He based his 2007 report on "information collected from a variety of independent and reliable sources."

The military has run the reclusive Southeast Asian country formerly known as Burma since 1962, refusing to hand over power after the National League of Democracy, the party led by opposition leader and Nobel laureate Aung San Suu Kyi, won a 1990 election.

The government in Yangon has promised to restore democracy through reforms including freeing political dissidents and drafting a new constitution. But there have been few signs of political or constitutional changes and Suu Kyi, 62, remains under house arrest without a telephone.

The junta says 10 people were killed in September's crackdown on peaceful monk-led demonstrations but Western governments say the toll is likely far higher.