Media playback is unsupported on your device Media caption The BBC's Orla Guerin reports amid "euphoric scenes" in Islamabad when the arrest order was announced

Pakistan's Supreme Court has ordered the arrest of PM Raja Pervez Ashraf and 15 others over corruption allegations, raising fears of a political crisis just months ahead of an election.

Mr Ashraf denies accepting bribes when approving power generation projects as minister for water and power in 2010.

Analysts say that the move is unlikely to lead to his immediate removal.

It comes as a populist cleric led thousands of protesters in Islamabad, demanding the government resign.

There was a mood of mass euphoria as the news of the court's order reached demonstrators, led by Tahirul Qadri. Some jumped for joy and others hugged, some crying.

Analysis The Supreme Court's order to arrest Prime Minister Raja Pervez Ashraf comes in a case the court has been hearing for over a year. Mr Ashraf is accused of accepting bribes in 2010, when he was the minister of water and power. This does not automatically lead to his unseating, but analysts say the timing of the court order is suspicious at a time of mass protest and just months ahead of an election The streets of Islamabad are clogged by anti-corruption protesters led by a Canadian cleric of Pakistani origin, Dr Tahirul Qadri. Since his arrival in the country last month, his critics have been accusing him of trying to derail the democratic system just months ahead of polls. There has been speculation that he may be fishing for a role for the military and the judiciary when it comes to the appointment of an interim government which will preside over those elections, due in May.

"So far we have not received anything from the Supreme Court in writing. The government, the law ministry and the prime minister have not received any order from the Supreme Court," Information Minister Qamar Zaman Kaira reportedly told private TV channel Geo.

"The timing of the decision should be noted. As far as I have been told, the prime minister's name is not mentioned in the Supreme Court order and hype has been created," he said.

The BBC's M Ilyas Khan in Islamabad says the timing may just be a coincidence - but to many observers it bolsters allegations that the cleric is backed by elements of the judiciary and military.

In recent years Pakistan's government, judiciary and powerful military have been at loggerheads.

Mr Ashraf's predecessor, Yousuf Raza Gilani, was forced out as prime minister last June after the Supreme Court convicted him of contempt for failing to pursue a corruption case against the president.

Mr Ashraf was appointed in his place, but many predicted that his tenure would also be troubled.

The Supreme Court order says the prime minister and the others should be arrested and produced before court within 24 hours. But correspondents say the prime minister's lawyers may find ways of delaying any appearance.

Dogged by controversy

There was no immediate statement from the government following the arrest order. President Asif Zardari was holding a meeting of leading figures in the ruling Pakistan People's Party (PPP) in Karachi, according to state broadcaster PTV.

Mr Ashraf is set to lead the party into general elections due in May. Most observers say they expect the balance of power in the forthcoming parliamentary polls to broadly stay the same unless turnout is high, which could allow minor parties to translate popular support into seats.

Mr Ashraf has long been a senior figure in the PPP, and has twice been a minister in the government which has been in power since 2008.

Raja Pervez Ashraf Born in 1950, Raja Pervez Ashraf comes from a landowning political family with strong connections to Sindh province

He has been active in national politics since 1988 but lost repeated parliamentary elections until the 2002 and 2008 polls

Since 2008 he has served as both water and power minister and information technology minister

But his time as water and power minister was dogged by power cuts and controversy over a power generation scheme

He denies charges of accepting kickbacks

But it was his tenure as minister for water and power which is dogged by controversy.

The government needed to generate more power to deal with electricity shortages, but there were accusations of corruption from the opposition about the so-called "Rental Power Projects" devised to solve the crisis.

Critics labelled him "Raja Rental" because of the kickbacks he is alleged to have taken - he has consistently denied these claims and left the water and power post in 2011.

But many analysts say this case could simply be a continuation of the long feud between the PPP-led government and the judiciary.

And there have also been chaotic scenes in Islamabad after a long-planned march from Lahore to the capital by Mr Qadri culminated in a mass rally.

Clashes briefly erupted on Tuesday before Mr Qadri addressed his thousands of supporters camped near parliament, vowing to continue his mass protest indefinitely.

The cleric has said he wants the military and judiciary to be involved in installing a caretaker government to oversee the forthcoming elections.

But the government has accused him of trying to postpone elections due in May.