Thailand’s pro-government “Red Shirts” have begun massing in Bangkok to challenge a bid by opposition protesters who claim they will try to install an unelected regime in the wake of the removal of the prime minister.

The dismissal of premier Yingluck Shinawatra and nine ministers by the Constitutional Court for the improper transfer of a top security official has plunged the restive kingdom deeper into crisis.

Officials said about 3000 police officers were on stand-by for the pro-government rally on the western outskirts of Bangkok on Saturday, with turnout expected to peak in the evening.

“We are ready to fight,” senior Red Shirt Kwanchai Pripana said.

“We will not use violence but we will use the power of the masses to fight for democracy.”

The Red Shirts have said they will keep up their protests for as long as necessary to defend the wounded administration.

Rival opposition demonstrators are demanding an unelected leadership be allowed to take the reins of the Southeast Asian nation and oversee vague reforms they say would tackle corruption.

Such a move would infuriate supporters of Yingluck and her elder brother Thaksin Shinawatra, who was deposed by royalist generals in a coup in 2006, an event that ushered in years of political turmoil.

A military crackdown on Red Shirt protests against the previous government left dozens dead in central Bangkok in 2010.

The spectre of the military seizing power also looms constantly over Thailand, which has seen 18 successful or attempted coups since 1932.

“The government is spending its energies hoping to keep military action at bay,” said Paul Chambers, director of research at the Institute of South East Asian Affairs at Chiang Mai University.

“I am afraid an army coup could be approaching,” he added.

Political violence has left at least 25 people dead and hundreds wounded in gun and grenade attacks by shadowy assailants in recent months, mostly targeting opposition demonstrators.

The fear is that armed elements on both sides of the political divide could seek to incite further unrest.

Police used water cannons on Friday against anti-government protesters attempting to enter a state security agency.

The opposition activists also surrounded a number of television stations in a move decried by rights campaigners as media intimidation.