Pakistani Prime Minister Yusuf Raza Gilani has filed an appeal against appearing before the Supreme Court in a contempt hearing for failing to re-open corruption cases against the president, his lawyer said on Wednesday.

The Supreme Court last week ordered Gilani to appear before it on February 13 to be charged with contempt of court in a case that has raised political tension.

I've filed the appeal, Gilani's lawyer, Aitzaz Ahsan, told reporters.

Gilani first appeared before the Supreme Court on January 19 to explain why he should not be charged with contempt for failing to re-open old corruption cases against President Asif Ali Zardari.

If convicted, he could face jail and the loss of office.

The legal tussle stems from thousands of old corruption cases thrown out in 2007 by a controversial amnesty law.

The government maintains Zardari, co-chairman of the Pakistan People's Party, which leads the coalition government, enjoys immunity as the head of state.

Zardari's government is the longest-running civilian administration in Pakistan's coup-marred history. But it has become deeply unpopular, criticised as corrupt and incompetent.

Political instability and brinkmanship has consumed the nuclear-armed country in recent years, preventing it from addressing crushing poverty and other economic ills, or containing a rampaging insurgency that is endangering the U.S.-led war effort in Afghanistan.

(Reporting by Serena Chaudhry; Editing by Chris Allbritton)