Thai police fired teargas Friday at protesters who called for the nation's Senate to aid their bid to topple the embattled government, two days after the prime minister was stripped of office.

Scenting blood after Wednesday's court decision to remove Prime Minister Yingluck Shinawatra, protest leader Suthep Thaugsuban handed a petition to the upper house urging it to decapitate a government they say has lost all legitimacy, and appoint a new premier.

"We want the president of the upper house and the members of the upper house to think about the way out for the country," said Suthep.

With the government weakened but still standing, the call for an appointed administration appears to lack legal grounds.

Earlier Suthep led thousands of protesters, who had fanned out from their main encampment in a park in the city's commercial district and brought traffic to a standstill in a day of choreographed actions.

Authorities said they briefly used water cannon and tear gas to hold off a hardcore group of anti-government protesters led by a Buddhist monk, who were attempting to enter a fortified police club.

The city's Erawan Emergency Centre said six people were taken to hospital after the incident at the police club.

With protesters back on the streets after a relatively quiet few months, fears are again simmering of street clashes between rival political groups.

The ruling Puea Thai party has replaced Yingluck with Niwattumrong Boonsongpaisan and is targeting July 20 elections to end the six-month political crisis, which has left the kingdom without a fully functioning government and chiselled away at the Thai economy.

But the Thai courts have now booted out three prime ministers linked to Yingluck's family, who have swept every poll since 2001.

The Thai army ousted Yingluck's billionaire brother Thaksin from power in a bloodless coup in 2006, sending the country spinning into political turmoil.

Bloodied but still standing

The situation remains highly combustible with pro-government "Red Shirts" due to mass in Bangkok's suburbs on Saturday, as Thailand's political crisis lurches into a dangerous new phase.

Both sides have hardcore armed supporters and Thailand's recent history has been scarred by bouts of political violence.

At least 25 people have been killed and hundreds more left wounded in gun and grenade attacks linked to six months of anti-government protests.

Although buffeted by the Constitutional Court's removal of Yingluck on abuse of power charges on Wednesday, the current Puea Thai administration has staggered on.

But the Red Shirts are outraged at Yingluck's removal from power, accusing the court of acting in cahoots with the street mob to boot out a third premier linked to their hero Thaksin.

"It seems like the same forces are united against the government... The courts and independent agencies and the street are working together," said Pavin Chachavalpongpun, associate professor at the Centre for Southeast Asian Studies at Japan's Kyoto University.

On Thursday the government won a legal reprieve as the kingdom's anti-graft panel stepped back from hauling more cabinet members into a separate indictment against Yingluck over a costly rice subsidy scheme.

There were fears the agency could have moved against the remainder of the government to complete a "judicial coup" and create a power vacuum that could have been filled by an appointed leader, as desired by the anti-government protesters.

They broadly come from the Bangkok-based establishment and middle-class, backed by royalist southerners, and revile Thaksin, who they accuse of massive corruption and perceive as a threat to the nation's beloved but ailing king.

They also allege the Shinawatras have drained the kingdom's coffers to sweeten Thaksin's rural electoral base in the poor but populous north and northeast, with populist policies such as the rice subsidy.

Thaksin's rural heartlands have powered his parties into power in every election since 2001, praising him for recognising their growing political and economic aspirations.

They accuse the Bangkok elite of attempting to steal power undemocratically by seeking to install an unelected "people's council" to oversee vaguely-defined reforms.

Thaksin lives overseas to avoid jail for corruption convictions he says were politically motivated.