Bangkok - Protest leaders camping outside Government House in Bangkok vowed Thursday to extend their demonstration until the government is dissolved.

The leaders of the so-called Red Shirts said since none of their demands had been answered they had no choice but to increase pressure on the government.

The Red Shirts, supporters of controversial former prime minister Thaksin Shinawatra, are calling for new elections and the resignation of Foreign Minister Kasit Piromya, a core leader of the royalist Yellow Shirts who seized Bangkok's two airports last year in a bid to oust a pro-Thaksin government.

The Red Shirts also Thursday marched to the National Anti-Corruption Agency to protest against its allegedly biased investigations into the dealings of the self-exiled Thaksin, the Thai News Agency Reported.

This week's protests by the Red Shirts, or the United Front of Democracy against Dictatorship (UDD), were designed to embarrass the government of Prime Minister Abhisit Vejjajiva before it hosts the 14th Summit of the Association of South-East Asian Nations (ASEAN) from Friday to Sunday in Cha-am, 130 kilometres south-west of Bangkok.

Protest numbers have shrunk from more than 10,000 on Tuesday to less than 1,000 and Abhisit appeared to have little trouble entering and exiting his office Thursday morning.

Red Shirt leader Jatuporn Prompan told reporters "the numbers of the street are just a token. We have huge support and a lot of power behind us. We can't let this government get away with (ignoring us)." (dpa)