Prime Minister Yousuf Raza Gilani arrived at Pakistan's Supreme Court on Thursday to face contempt of court proceedings that could see him disqualified as a member of parliament if convicted.

It is only the second time that the court has initiated contempt proceedings against a sitting prime minister, plunging Gilani's weak government deeper into a crisis that could force early elections within months.

Pakistan's highest court summoned Gilani to explain his refusal to ask Switzerland to re-open graft cases against President Asif Ali Zardari.

The government is also under immense pressure from the army and judiciary over a memo asking Washington to prevent a feared coup last May, compounding widespread belief that the administration is staggering on its last legs.

Appearing relaxed, waving and smiling for the battery of television cameras lined up outside the court, Gilani swept inside the building at around 9:25 am (0425 GMT) under a heavy presence of police and paramilitary.

Several senior cabinet ministers and leaders of allied political parties also arrived to attend the proceedings.

"The court wanted some clarifications and the prime minister decided to attend himself. This is something the court and media should appreciate," Interior Minister Rehman Malik told reporters.

A spokesman for the ruling Pakistan people's Party (PPP), Qamar Zaman Kaira, said Gilani's acceptance of the court summons "shows his respect" for the country's highest court.

"We fight cases in the courts, we do not fight with courts," Kaira added.

Officials have been tight-lipped on what the prime minister and his lawyer will say, but commentators doubt that Gilani will decide to risk six months in jail and being stripped of office.

His lawyer, Aitzaz Ahsan, has said Gilani may as well do what the court wants and write to Switzerland because Zardari has immunity from prosecution as long as he remains in office.

Ahsan is a senior leader in Zardari's Pakistan People's Party (PPP) and well respected by the judiciary for his role at the vanguard of a lawyers' movement that forced the government to reinstate independent judges in March 2009.

Among the options for the Supreme Court judges are to find Gilani in contempt, which would disqualify the prime minister from office, and forcing early elections.

Analysts say Gilani has to either resign or find a way of satisfying the court order if he wants to keep his job.

Some have suggested that the PPP could sacrifice Gilani to protect the president, who has been accused over the controversial May 10 memo that sought US assistance to curb the powerful military.

His ambassador to Washington, Husain Haqqani, was forced to resign and a judicial inquiry is examining who was responsible for the note.

The allegations against Zardari were frozen by an amnesty imposed by former military ruler Pervez Musharraf in 2007. But since it expired in late 2009, the judiciary has demanded that the government revisit the cases.

The domestic turmoil has temporarily overshadowed a drastic deterioration in relations with the United States that plummeted disastrously in 2011 over a series of crises, largely America's covert killing of Osama bin Laden on May 2.