Pakistan’s embattled Prime Minister Yousaf Raza Gilani on Thursday said conspirators were plotting to bring down his government and delivered an unprecedented tirade against the powerful military.

In astonishing confirmation that he fears being ousted, he angrily denied the government was subservient to the Army, long considered the chief arbiter of power in Pakistan as his administration grapples with a damaging scandal.

Pressures are at boiling point over a memo, allegedly written with approval from the president, asking for US help to prevent a feared military coup after Osama bin Laden was killed in May.

Rampant speculation that President Asif Ali Zardari could be forced out of office over the scandal and illness has refused to die, despite his return to the capital following two weeks of medical treatment in Dubai.

"I want to make it clear today that conspiracies are being hatched here to pack up the elected government," Gilani told a gathering at the National Arts Gallery, without naming anyone.

"But we will continue to fight for the rights of people of Pakistan whether or not we remain in the government," Gilani said, declaring himself the country's longest serving premier, with 45 months on the job.

He was the most senior member of the government to speak so candidly about frenzied speculation pumped out daily by the local media about the future of an administration made unpopular by recession, power cuts, scandal and inflation.

Two weeks ago, interior minister Rehman Malik dismissed rumours that a coup could overthrow the government, but Gilani's remarks appeared to show that members of the administration believe their early departure is all too possible.

Zardari and his government have earned praise for successfully navigating scandals and calls for their resignation since taking office after the Pakistan People's Party (PPP) won elections in February 2008.

But any decision from the Supreme Court to investigate the memo, as recommended by the military, would build significant pressure on the President.

Elections are not due until February 2013, but the opposition has begun campaign rallies in earnest and many observers expect polls some time in 2012. No civilian leader in Pakistan has ever completed a full term in office.

Although the military has ruled Pakistan for more than half its existence and seized power in four coups, analysts rule out any imminent takeover.

At the National Arts Gallery, Gilani called the army "disciplined", saying that they "follow the constitution" and "will remain under the government".

But heading off questions in Parliament, he took aim at the military over reports that the defence ministry conceded to the Supreme Court that it had no control over the armed forces or ISI intelligence agency.

"If they say that they are not under the ministry of defence, then we should get out of this slavery, then this Parliament has no importance, this system has no importance, then you are not sovereign," he told lawmakers.

"Nobody is above the law, all the institutions are subservient to the parliament," Gilani insisted.

Appearing to lose patience, he said the government had stood by the security services over a storm of American pressure over the Osama bin Laden killing, the November 26 Nato attack and the 2008 attacks on Mumbai.

"In the worst circumstances we doubled their salaries. They have to be accountable to Parliament."

"We are being asked by the judicial commission (examining the May 2 US raid that killed Bin Laden raid and how the Al Qaeda leader lived in Pakistan undetected) about issuance of visas (to Americans).

"But I want to ask how was (Bin Laden) living here for the past six years? On what type of visa was he living here? Why was security not taken care of, if he entered in Pakistan without a visa?"

Former Prime Minister Nawaz Sharif this week demanded snap elections.

The Supreme Court adjourned until on Friday a hearing on whether to investigate the memo allegedly written by one of Zardari's closest advisers to ask for American help over a feared military coup in May.

Husain Haqqani, Pakistan's ambassador to Washington, was forced to resign over the scandal and flatly denies the accusations from a US businessman.