Pakistan's prime minister, Raja Pervaiz Ashraf, has been arrested in connection with a scandal involving contracts for power stations. Photograph: Waqar Hussein/EPA
Pakistan's supreme court has ordered the arrest of the country's prime minister on corruption charges, heightening already extreme political uncertainty and fears the country's fragile democracy could be derailed.
The news broke on television stations as a Muslim cleric addressed tens of thousands of protesters who have massed on the capital city for an extended sit-in to protest against corruption and electoral malpractice by Pakistan's politicians.
Raja Pervaiz Ashraf's arrest was ordered in connection with a long-running scandal involving contracts for power stations, but the timing of the intervention by Pakistan's highly political judiciary raised instant suspicions.
The country's political class has for weeks feared that a so-called "million man march" led by the Islamic scholar Tahir-ul-Qadri would be used as a pretext to postpone elections scheduled for the next few months.
In the early hours of Tuesday morning, Qadri had already declared to his supporters that the "false mandate of the rulers is over" and ordered President Asif Ali Zardar to dissolve parliament immediately.
"Zardari has become an ex-president," said Qadri while addressing the crowd from behind a bulletproof screen placed on top of a sea container in the middle of Islamabad's central avenue. "Dissolve the assembly or the people will do it," he said.
Many commentators have questioned Qadri's motives, fearing he is a stalking horse for the powerful military and judiciary. Both institutions are highly antagonistic to civilian politicians, whom they regard as corrupt and unable to grapple with Pakistan's acute problems.
During a second Tuesday speech by Qadri to thousands of people who had camped on the street overnight, the cleric confirmed many people's fears by heaping praise on the army and judges.
He said: "There are only two institutions in Pakistan that are functioning and doing their duties of the people. One is the judiciary of Pakistan and one is the armed forces of Pakistan and nothing else."
Prior to the supreme court's announcement it was unclear whether Qadri would succeed in achieving his demands for government dissolution and extensive electoral reforms designed to block incompetent politicians from gaining office.
With crowd numbers appearing to fall far below the million marchers promised by Qadri, or even the 100,000 some independent observers had predicted, some thought the protest in Islamabad would degenerate into an awkward standoff.
But after news broke the crowd erupted in celebrations and cries of "long live the supreme court".
Breaking into English, Qadri declared: "Victory, victory, victory by the grace of God!"
Ashraf has served as prime minister since June last year after Yousaf Raza Gillani was forced from office after the country's top judge found him guilty of contempt of court.
The Karachi stock exchange plunged on the news of the arrest order for Ashraf as investors feared yet more instability in Pakistan.