BANGKOK (AFP) - Thai Prime Minister Abhisit Vejjajiva said Thursday he would consider asking China to help bring former premier Thaksin Shinawatra home, days before the fugitive ex-leader was to speak in Hong Kong. Thaksin is scheduled to speak at the Foreign Correspondents Club in the southern Chinese city on Monday, and Abhisit said he was determined to see the former premier serve a two-year jail sentence for abuse of power. "We are checking on legal details whether we can ask for his extradition. If it is possible then we have to take action," Abhisit told reporters. "We want all Thais to be under the same law," he added. A Thai foreign ministry official confirmed that Thailand had signed an extradition treaty with China in 1993. Such legal processes between nations, however, are usually lengthy and complicated. Hong Kong is a special administrative region of China. Abhisit also urged Thaksin to tread carefully in his address in Hong Kong " a rare public appearance for the telecoms tycoon who was overthrown in a military coup in September 2006 and now lives in exile to escape jail. "If he makes any bad allegations against Thailand, the government will clarify (his comments)," the premier said. Meanwhile, protesters besieging the Thai premier's office vowed a "protracted" campaign to unseat his government as their rally entered a third day Thursday, threatening further turmoil on the eve of a key summit. Thousands of supporters of ousted premier Thaksin Shinawatra first surrounded Government House on Tuesday demanding new elections, and the red-clad demonstrators have camped outside the compound since. Numbers had dwindled to about 800 on Thursday, police said, but protest leader Jatuporn Prompan told reporters they would fight on until they had toppled Prime Minister Abhisit Vejjajiva's two-month-old administration. "As the protest enters a third day, we still have not got an answer from the prime minister on our demands," he said. "Therefore we have upgraded our movement to overthrow the government by every means. Protests will be protracted and widespread." On Thursday, crowds headed to the office of the National Counter Corruption Commission, set up by the junta that overthrew Thaksin in 2006, where they pelted eggs at the building and burnt a wreath, local television showed. The protesters are also calling for the resignation of Foreign Minister Kasit Piromya because of his ties to anti-Thaksin protest group the People's Alliance for Democracy (PAD). Kasit defended his record to reporters at the ASEAN summit and refused to quit. "I am such a nice person and serving society to the best of my ability," Kasit said. "I cannot read the hearts and minds of the Red Shirts and I don't see the logic of their not liking me." The Red Shirts want PAD leaders to face legal action for their week-long seizure in late November-early December of Bangkok's two airports, which only ended when a court dissolved the Thaksin-linked former ruling party. The airport closures also forced the postponement of the ASEAN summit, which was originally scheduled for December. Despite the protesters outside his office, Abhisit was able to enter Government House on Thursday. His Democrat Party came to power in December after a court dissolved the People Power Party a year after its election. "The government will carry on its work as normal. Protests are common and allowed under the constitution," Abhisit told reporters.