Pakistani Prime Minister Yousuf Raza Gilani said Monday he will appear before the Supreme Court later this week to face a contempt notice for failing to reopen a graft case against President Asif Ali Zardari.

The Supreme Court ordered Gilani to appear before the court on January 19. If convicted of contempt of court, Mr. Gilani can be sent to jail and removed from his post.

The court initiated contempt proceedings against Gilani early Monday after the government failed to ask Swiss authorities to reopen a corruption case against the president that dates back to the 1990s and involves the jurisdiction of the Swiss courts. Islamabad has refused, saying Mr. Zardari has immunity as the head of state.

The court order escalates the pressure on Pakistan's civilian leadership, which faces separate court battles and high tensions with the country's powerful military.

A Supreme Court-appointed panel is investigating the origins of an unsigned memo in which Pakistan's civilian government allegedly asked for U.S. help in reining in the Pakistani military, following the U.S. raid that killed Osama bin Laden last May.

The existence of the document came to light in October when Pakistani-American businessman Mansoor Ijaz accused the then-Pakistani ambassador to the United States, Husain Haqqani, of writing the memo. Haqqani denies he wrote the document and has since resigned.

U.S. military officials confirmed that the top U.S. military officer at the time, Admiral Mike Mullen, received the memo but did not find it credible.

Last week, Mr. Gilani accused army chief General Pervez Ashfaq Kayani and Inter-Services Intelligence head Lieutenant General Ahmad Shuja Pasha of acting unconstitutionally by making unilateral submissions to the ongoing inquiry.

In response, the military said his remarks will have “very serious ramifications,” and warned of “grievous consequences” for the country.