BANGKOK -- Thai police arrested Friday one of nine anti-government protesters responsible for leading thousands of demonstrators to besiege the government's office compound, a police spokesman said.

Chaiwat Sinsuwong, one of nine members of the People's Alliance for Democracy (PAD) wanted on arrest warrants for treason, was picked up by police on a Bangkok road.

"He was arrested by metropolitan police forces as he was about to enter the expressway," Major General Surapol Tuanthong told Agence France-Presse. "He is being detained at border police headquarters for questioning now."

A court issued arrest warrants for the PAD leaders on August 27, a day after they led 15,000 people to protest at the doors of the government offices demanding the administration quit.

Five thousand protesters set up camp in the grounds, many of whom remain, refusing to budge despite a new prime minister and cabinet being appointed last month.

Charges outlined against the nine leaders include treason, assembly of more than 10 people with illegal aims and refusing to disperse.

Under Thai law a person convicted of treason can face life imprisonment or the death penalty.

The eight other PAD members still wanted by police include media tycoon and PAD founder Sondhi Limthongkul, retired general Chamlong Srimuang, activists Somkiat Pongpaibul and Somsak Kosaisuk, and MP Pibhop Dhongchai.

PAD spokesman Suriyasai Katasila and rally organizers Therdpoom Chaidee, Amorn Amornrattannond and Suriyasai Katasila are also sought on arrest warrants.