Burma’s military security forces have surrounded the headquarters of the ruling Union Solidarity and Development Party (USDP) in the capital, Naypyidaw, and prevented party members in the compound from leaving, party sources in the building said on Thursday morning.

A DVB reporter confirmed that at least 10 vehicles were patrolling or entering the compound throughout the night.

Reuters has reported that several trucks of soldiers and police officers arrived at the compound at around 10 pm.

“We have not been allowed to move around since late yesterday,” said one party member, cited by Reuters.

Meanwhile, AFP has quoted the son of parliamentary House Speaker Shwe Mann saying that “guards” are currently at his father’s house.

“Police entered the party compound last night. Since then, no one was allowed in or out,” Toe Naing Mann told AFP on Thursday morning.

Toe Naing Mann, who said he was monitoring the situation through contacts from Rangoon, said it was not clear what was behind the move by security personnel late Wednesday.

The moves comes amid an ongoing tussle for control of the ruling USDP ahead of the November elections.

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Recent months have seen growing talk of animosity between Shwe Mann and President Thein Sein, both former generals who shed their uniforms to take part in controversial 2010 polls that heralded a new quasi-civilian government which has ushered in sweeping reforms.

Shwe Mann has publicly welcomed the idea of working closely with opposition leader Aung San Suu Kyi, and has set himself up in opposition to the still powerful army on key issues — including on constitutional reform debates that centred on reducing the military’s political power.