Pakistan's top court ordered the arrest of the prime minister in a corruption case Tuesday, the latest clash between the government and a judiciary that has repeatedly pressured the country's political leaders.

The ruling is sure to inflame the already antagonistic relationship between the court and the government, pushing the country toward yet another political crisis.

It also could provide ammunition to Tahir-ul-Qadri, a firebrand Muslim cleric who recently returned from Canada and was leading tens of thousands of people in a second day of rallies in Islamabad to press for the removal of the government, which he criticized as corrupt and indifferent to the common man.

The Supreme Court order against Prime Minister Raja Pervaiz Ashraf was related to a case involving private power stations set up to provide electricity to energy-starved Pakistan. The judges are investigating allegations that the bidding process was marred by corruption.

Chief Justice Iftikhar Chaudhry ordered the arrest of 16 people involved in the case, including Ashraf, who previously served as minister for water and power, said the written court order.

Immunity from prosecution while in office

An adviser to the prime minister, Fawad Chaudhry, said any attempt to arrest the prime minister would be unconstitutional since he enjoys immunity from prosecution while in office.

"We consider it a judicial coup, and it is part of a greater plan to derail democracy," Chaudhry said.

The Supreme Court clashed repeatedly with the government over the last year, especially over an old corruption case against President Asif Ali Zardari in Swiss courts. Pakistan's top court convicted Ashraf's predecessor, Yousuf Raza Gilani, of contempt of court for refusing to reopen the case and ousted him from office.

'We consider it a judicial coup, and it's part of a greater plan to derail democracy.'— Fawad Chaudhry, an adviser to the prime minister

The judges pressured Ashraf as well, and the government finally agreed to the court's demand to ask the Swiss to pursue the case — which Swiss authorities have said privately they have no intention of doing because Zardari enjoys immunity while in office.

It was unclear whether there was any connection between the Supreme Court's order and Qadri's rally. But some speculated it was a scripted one-two blow by the chief justice and the cleric to strike at their opponents in the government.

Cleric says only judiciary, army serving the people

Qadri has seized on alleged corruption by Pakistani politicians to rally support for his protest against the government. The cleric rocketed to national prominence after his return from Canada late last year, and his message has galvanized many Pakistanis who say the government has brought them only misery.

But critics fear that Qadri and his demands for election reforms may derail the country's upcoming democratic elections, possibly at the behest of the country's powerful military — allegations denied by the cleric.

Those concerns could intensify following a fiery speech he delivered to protesters Tuesday in which he condemned the country's politicians as corrupt thieves and lavished praise on both the Supreme Court and the military, which has a history of toppling civilian governments in coups.

The 61-year-old cleric spoke from inside a bulletproof vehicle parked several hundred metres from parliament, facing hundreds of police in riot gear who formed a human barrier against at least 30,000 demonstrators packed into the main avenue running through Islamabad. Many waved green and white Pakistani flags and cheered as Qadri spoke.

He said there are only two institutions in Pakistan that "are functioning and performing their duties to fulfill the needs of the people."

"One is the judiciary of Pakistan, and one is the armed forces of Pakistan, and nothing else," said Qadri.