Pakistan's top court Monday found embattled Prime Minister Yousuf Raza Gilani in contempt for not complying with orders related to re-opening corruption cases and summoned him to appear in person.

The move escalates the pressure on Pakistan's weakened civilian government, which faces separate court procedures that could unseat its leadership and force early elections at a time of soaring tensions with the powerful army.

It marks only the second time that contempt of court procedures have been initiated against a sitting prime minister in Pakistan. Gilani was summoned to appear in court on Thursday.

In November 1997, prime minister Nawaz Sharif was also found in contempt in a case which ultimately led to the resignation of president Farooq Leghari.

"The Supreme Court has issued a contempt of court notice to the prime minister for not complying with its orders," Judge Nasir-ul-Mulk told the court which met to debate how to proceed on graft charges against the president.

"He has been directed to appear personally on January 19."

The Supreme Court wants the government to write to Swiss authorities demanding that they re-open old corruption cases against President Asif Ali Zardari, which the government has so far refused to do.

Zardari and his Pakistan People's Party (PPP) leadership say the president has immunity from prosecution as long as he remains in office.

On Monday, judges convened to debate six options on how to proceed on graft charges against Zardari, which included finding Gilani in contempt, disqualifying the prime minister and president, and holding early elections.

Attorney General Maulvi Anwarul Haq told the court he had been given no instructions from the government on how to proceed over the options.

"We are left with no option but to issue a show cause notice to the prime minster of Pakistan (for him to explain) as to why he shall not be proceeded against for contempt of this court," responded Mulk.

Zardari is also under pressure from an investigation into who was behind efforts to solicit American help to prevent a coup apparently feared in the aftermath of Osama bin Laden's death and to clip the power of the army.

Zardari's close aide, Husain Haqqani, was forced to resign as ambassador to Washington over a secret memo written last May and the Supreme Court ordered an inquiry on December 30 following a demand from the country's chief spymaster.

Later Monday, the lower house of parliament is to hold a confidence vote in the civilian leadership amid the simmering row with the military.

Tensions reached fever pitch last week when the prime minister sacked his defence secretary, who was considered close to the generals. The army then warned of "potential grievous consequences for the country".

The army has carried out three coups in Pakistan, but analysts believe it has no appetite for another direct takeover, instead preferring to force early elections behind the scenes in concert with pressure from the courts.

Gilani has moved to calm tensions, praising the military's role in a meeting of the cabinet defence committee attended by army chief General Ashfaq Kayani.

The commission probing "memogate" has been given four weeks to find out who was responsible for the note and is expected to determine later this month whether Islamabad endorsed it.

The attorney general told the commission he had been unable to obtain crucial evidence -- Blackberry message data sent between Haqqani and businessman Mansoor Ijaz, who claims to have acted as a go-between on the memo.

He said the government had written to Blackberry's makers, but that Research In Motion said it was impossible to release such records without the customer's permission.

Ijaz, who has American nationality, has not visited Pakistan since revealing the existence of the memo in the Financial Times in October.

His Pakistani lawyer, Akram Sheikh, said Ijaz feared for his life and that of his family should he visit Pakistan, but Sheikh said Ijaz would apply for a Pakistani visa in Switzerland.

Commission head Justice Qazi Faiz Eisa asked Sheikh to give a definite date for Ijaz's appearance.