Gilani was charged with contempt by the country's highest court in Februaryfor refusing to write to the Swiss authorities to ask them to re-open corruption cases against President Asif Ali Zardari.

"The court will announce judgment in the case on Thursday (April 26)", Gilani's counsel Aitzaz Ahsan told reporters in Islamabad.

Asked if the prime minister will appear in person, he said: "I will inform him about it today and he will Insha Allah (God willing) come to the court."

He said the maximum punishment Gilani could face if convicted was six months in prison, but he was hopeful the judges would acquit his client.

Gilani is Pakistan's first sitting premier ever to face criminal charges and if he is given a jail sentence he could be disqualified from office.

The Swiss shelved the cases against Zardari in 2008 when he became president and a prosecutor in Switzerland has said it will be impossible to re-open them as long as he remains head of state and is immune from prosecution.

Gilani insists that Zardari has full immunity. But in December 2009 Pakistan's Supreme Court overturned a two-year political amnesty that had frozen investigations into Zardari and other politicians.

Zardari and his late wife, former premier Benazir Bhutto, were suspected of using Swiss accounts to launder about $12 million allegedly paid in bribes by companies seeking customs inspection contracts in the 1990s.

The president, who is so tainted by graft allegations, has already spent 11 years in jail on charges ranging from corruption to murder. (AFP)