The court order came as an enigmatic preacher turned politician, Muhammad Tahir ul Qadri, addressed thousands of supporters outside Parliament and repeated calls for the government’s ouster. In earlier speeches, he said that a caretaker administration led by technocrats should take its place.
The confluence of the two events stoked growing speculation that Pakistan’s powerful military was quietly supporting moves that would delay general elections that are due to take place this spring, most likely through the imposition of a military-backed caretaker administration.
“Victory, victory, victory. By the grace of God,” said Mr. Qadri at the conclusion of a speech to his supporters, who have vowed not to leave a public square outside Parliament until their demands are satisfied.
It was not certain that the events were linked. Some analysts said that in ordering the prime minister’s arrest, the court, which is led by the independent-minded chief justice Iftikhar Muhammad Chaudhry, was simply taking advantage of anti-government sentiment generated by Mr. Qadri to pursue its longstanding grudge against President Asif Ali Zardari.
Whatever its motivations, the court’s actions added to the chaos in Pakistan, with the stock market dropping 3 percent after word of the court’s order came down.
In the order issued Tuesday, the Supreme Court ordered the National Accountability Bureau, a government body that investigates graft, to arrest Mr. Ashraf and 15 other senior current or former officials, including a former finance minister and a former finance secretary.
The case relates to longstanding allegations that Mr. Ashraf took millions of dollars in kickbacks as part of a deal to build two electricity plants while serving as minister for water and power between March 2008 and February 2011.
The order comes more than a year after two opposition figures filed a complaint in the Supreme Court against Mr. Ashraf. Three months later, in March 2012, the court ruled that the power plants were illegal, ordered their closure, and instituted proceedings against Mr. Ashraf.
The case has particular political resonance because Pakistan’s energy crisis, which has seen severe electricity rationing across the country, is the source of some of the main complaints against the government.
The information minister, Qamar Zaman Kaira, said the government had not received any official notification of the order to arrest Mr. Ashraf.
Fawad Chaudhry, a senior adviser to the prime minister, said that any such order would be "illegal and unconstitutional."
"Under the law, the court cannot arrest him," he said President Zardari called a meeting of senior advisers at his Karachi residence to discuss the crisis late Tuesday, Mr. Chaudhry added.
Mr. Zardari’s supporters have painted the prosecution as part of a politically-motivated drive by Justice Chaudhry to unseat Mr. Zardari. Mr. Ashraf came to power last June after the Supreme Court forced his predecessor, Yousaf Raza Gilani, to resign from office over another corruption-related case.
Whether there was any link between the court order and Mr. Qadri’s march on Islamabad – billed by the preacher as a “million man march” but in reality far smaller – the timing was certainly striking.
Mr. Qadri stormed onto the political scene in Pakistan after returning from a seven-year stint in Canada, where he also holds citizenship, armed with considerable funding that he has used for an intensive television advertising campaign and large rallies.
In his speech Tuesday, which was peppered with emotional Islamic references, he demanded the immediate resignation of the government and painted the country’s elected politicians as “criminals” who deserved to be prosecuted for corruption.
“There is no Parliament. There is a group of looters, thieves and dacoits!” he said in a thundering voice, pointing to the building behind him. “Our lawmakers are the lawbreakers.”
In contrast, Mr. Qadri offered fulsome support for the military and the Supreme Court, both of which have been at odds with Mr. Zardari’s government at various points in recent years. “Now only two institutions are there – the judiciary and the armed forces,” he said.
Responding to the allegations that he is secretly supported by the military, Mr. Qadri said he was supported by Allah, the Prophet Muhammad and the 180 million people of Pakistan.
The government’s five-year term of office ends in mid-March. Under the constitution, elections are to take place within the following 60 days.
But Ayaz Amir, an opposition politician, said the crisis could actually benefit the government as it would enable it to play the “victim card.”
The developments raise doubts about the government’s ability to make headway in Pakistan’s efforts to achieve stability as a democracy. Should Mr. Ashraf’s administration complete its term and hold peaceful elections, it would be the first such transfer of power in Pakistan’s history.
But speculation that Mr. Qadri or the court could derail that transition grew steadily as events unfolded on Tuesday.
Theories about a link between the two players and the military are not easy to reconcile. Over the last year, Justice Chaudhry has openly clashed with top generals, as part of his court’s bid to carve out its independence from both civilian and military rulers.
Justice Chaudhry has stressed that his court will not act as a rubber stamp to military rule, as previous courts have, and earlier on Tuesday he reportedly stressed the importance of holding elections by mid-May.
