Demonstrations kicked off in November after Thailand's lower house passed a controversial amnesty bill, which critics said could allow former leader Thaksin Shinawatra to return without serving time in jail.
Mr Thaksin, one of the most polarising characters in Thai politics, was ousted in a military coup in 2006. He now lives in self-imposed exile overseas, but remains popular with many rural voters.
The amnesty bill, which was proposed by his sister Yingluck Shinawatra's Pheu Thai Party, was eventually rejected by the Senate. However, anti-government protests have continued.