BANGKOK - THAILAND'S parliament on Friday asked the Senate speaker to mediate in a deadlock between the government and a radical protest group whose supporters have mounted an unprecedented siege of the prime minister's office.

Speaker Prasopsuk Boondet, a former judge, was named as the mediator after he met with the head of the opposition Democrat Party and the deputy speaker of the House of Representatives, the lower house of Parliament. The Senate is the upper house.

'The speaker has agreed to find a way to get the two sides to sit down and talk to find a way out,' Democrat leader Abhisit Vejjajiva said.

The effort indicates the growing frustration among politicians over the prolonged crisis resulting from the campaign by the People's Alliance for Democracy to oust Prime Minister Samak Sundaravej from office.

On Thursday, Mr Samak said he would not quit but would hold a referendum on whether the alliance's campaign was justified.

Alliance leaders rejected the idea, and most analysts say it would be a futile exercise and divide the country.

Mr Samak did not immediately respond to the proposed mediation but insisted he will not negotiate with the alliance.

'No, that won't be necessary,' he told reporters. However, he did not outright reject dealing with Prasopsuk.

Thousands of alliance members took over the compound of Mr Samak's office, the Government House, on Aug. 26 and remain camped there, refusing to budge until he quits. It is the first time in history that the seat of government has been overrun by civilians.

Prasopsuk 'will be meeting with different people including the army chief and the PAD leaders to see what solution they can find to end the crisis', said Democrat Party spokesman Ong-art Klampaiboon.

Mr Panithan Wattanayagorn, a political analyst from Bangkok's Chulalongkorn University, said Mr Prasopsuk has a reputation of being fair and honest.

'It now depends on whether the two sides would be willing to talk and come up with a solution. It doesn't look like either side would budge easily,' he said.

The protesters accuse Mr Samak of being a stooge of former Prime Minister Thaksin Shinawatra, who was removed from power by a military coup in 2006 following months of street protests by the alliance.

Mr Samak came to power in general elections held by the military government in December 2007.

The alliance, a loosely knit group of royalists, wealthy and middle-class urban residents, and union activists, says the elections were fraudulent. It says Mr Samak is running the government as a proxy for Thaksin while he is in exile in Britain.

The alliance wants Parliament to be revamped so most lawmakers are appointed rather than elected, arguing that Thailand's impoverished rural majority is too susceptible to vote buying.

The government's failure to resolve the deadlock has raised fears of an economic downturn, especially in Thailand's crucial tourist industry, which is particularly susceptible to concerns about political instability.

On Friday, Mr Samak said he will meet with security officials in the next few days to discuss whether to lift the state of emergency he imposed in Bangkok on Tuesday.

Police warned against street protests after a gunman on the back of a motorcycle opened fire on a crowd of about 100 students demonstrating against Mr Samak late on Thursday, injuring two slightly.

'We explained to the students last night that the city is under the state of emergency - and they understood and dispersed,' said police spokesman Surapol Tuantong.

'The situation is very politically charged. Right now, it's not a good idea to gather,' he said. 'There are many parties involved and when something like this happens, it's hard to find the perpetrators.'

On Friday, about 500 students demonstrated outside police headquarters to demand a probe into the shooting. -- AP