
"With every incident that has happened, we must uphold the rule of law," Abhisit told reporters at Government House.
The People's Alliance for Democracy protesters included Democrat MP Somkiat Pongpaiboon, who is one of the PAD leaders.
Abhisit said he had told Somkiat not to use his position as an MP to gain immunity.
It has been almost four months since a prime minister - Samak Sundaravej - has been able to work at Government House. His successor Somchai Wongsawat was unable to do so at all, due to the PAD's occupation of the compound.
In an attempt to oust the People Power Party-led government, the PAD occupied Government House for almost 100 days from late August. It only left the compound early this month.
Yesterday was set as "Big Cleaning Day" for the seat of government.
The PAD protesters also blockaded Suvarnabhumi and Don Mueang airports for eight days last month, dispersing on December 3.
The blockade of the airports is estimated to have caused huge financial damage to Airports of Thailand, airlines and other operators, besides leaving about 350,000 tourists stranded.