Bangkok - Two grenades were fired into Thailand's anti-corruption office, police said on Friday, the latest attack on an agency that has lodged a case against the embattled prime minister that could lead to her impeachment.
Prime Minister Yingluck Shinawatra is due to defend herself Monday at the National Anti-Corruption Commission against charges that she failed to stop corruption and stem huge losses in the government's flagship rice-buying programme.
Yingluck's supporters have been protesting at the commission's compound for several days and camping out in front of it.
No one was injured from the grenades, which were thrown into the compound late on Thursday, deputy national police chief General Ake Angsananont told reporters. A building was slightly damaged at the compound in Nonthaburi province, outside Bangkok.
Police sealed off the area and searched for suspects. They seized a cache of weapons, including a grenade launcher, hand grenades, a rifle and two guns, and arrested four of the pro-government protesters in an area close to the commission. They were investigating whether those arrested were linked to the attack.
It was the second grenade thrown at the NACC this week, and the latest in a string of apparently political related grenade attacks that have included targets such as the Criminal Court, the attorney general's office and the home of a high-profile judge.
The attack came hours after the NACC rejected Yingluck's request to extend the Monday deadline for her defence. It had already granted an initial 15-day extension.
If the NACC indicts Yingluck on charges of dereliction of duty, the case would be forwarded to the Senate, which would vote on whether to impeach her.
The case comes after several months of anti-government protests against Yingluck to demand her resignation on grounds that she is corrupt and is serving as a proxy for her brother, former Prime Minister Thaksin Shinawatra.
The protests have eased in recent weeks but are set to be revived on Saturday for a mass rally in Bangkok.