Police Commissioner Adul Saengsingkaew has ordered security to be beefed up to protect personnel at many independent organisations - including judges - following the Constitutional Court's nullification of the February 2 general election.
Police stations throughout the capital were told to pay more attention to the offices of the Constitutional Court, the Election Commission, the National Anti-Corruption Commission and other independent bodies, police spokesman Piya Uthayo said.
The red-shirts have accused independent organisations of conspiring to topple the caretaker government under Yingluck Shinawatra.
The Constitutional Court ruled on Friday that the February 2 election was unconstitutional, ending Yingluck's hope of using the poll to return to power.
The anti-graft body is set to begin impeachment proceedings against Yingluck and some of her ministers for negligence in not preventing corruption in the rice-pledging scheme.
Anti-government protest leader Suthep Thaugsuban said recently that he would call another big rally on Saturday to put more pressure on Yingluck to step down, paving the way for an unelected government and reforms amid moves to try to force the Shinawatra clan from politics.
Moves by independent bodies and anti-government protesters have angered red-shirt supporters of the government, who threatened to call a huge rally to "protect" the government and democracy in early April.
Piya said the chiefs of all police stations in Bangkok had to assign security officials to guard all judges and senior officials of independent organisations.
He said police had to set up a security grid in risky areas, mostly near the offices of key agencies and the homes of top officials.