Several trucks of soldiers and police began surrounding the ruling party's compound late Wednesday, with the blockade extending into the early morning hours, officials said.

"Police entered the party compound last night. Since then no one was allowed in or out," Toe Naing Mann, the son of parliament speaker and Union Solidarity and Development Party (USDP) leader Shwe Mann, told the news agency AFP Thursday morning.

Party chief Shwe Mann and President Thein Sein are former military generals seeking to run for president in the November 8 elections.

Both men are former military officers who have been using the USDP as a vehicle to transform from army elite to political elite as Myanmar inches from military dictatorship toward democracy.

Elections slated for November

This autumn's presidential poll is expected to include opposition leader Aung San Suu Kyi, who has risen to international prominence as a democracy campaigner.

Shwe Mann has publicly welcomed the prospect of working closely with Suu Kyi and has set himself up in opposition to the still powerful army on key issues - including on constitutional reform debates that centered on reducing the military's power and influence.

It was not apparent Thursday morning who was behind the security deployment around the party office.

But the military, which ruled Myanmar for 49 years, maintains an effective veto over the civilian government and has resisted recent constitutional reform that would weaken its powers.

jar/mkg (Reuters, AFP)