ISLAMABAD: Pakistan has sent a letter to Swiss authorities asking that they reopen a money-laundering case against President Asif Ali Zardari after an amnesty protecting him from graft prosecution was struck down by the Supreme Court, a government lawyer said Wednesday.

The move raises the prospect Zardari could be investigated while in office and possibly convicted, greatly weakening his rule or ending it as the country battles al-Qaida and the Taliban. He has denied any wrongdoing and insists he has immunity from prosecution because he is president.

Zardari and his late wife Benazir Bhutto were found guilty in absentia in a Geneva court in 2003 of laundering millions of Swiss francs (dollars). They were handed six-month sentences and fined, but both punishments were automatically suspended when they appealed.

Swiss authorities abandoned the case in 2008 after the Pakistani government asked them to. The case was among thousands dropped as a result of a controversial amnesty that was part of a power-sharing deal that allowed Bhutto to return from exile and contest elections.

The amnesty was scrapped in December by the Supreme Court, which is led by a judge whom Zardari supporters say his hostile to his rule.

On Wednesday, a lawyer for the government's anti-corruption agency said that as a result of that ruling the agency had sent a letter to the Swiss attorney general asking that the probe be reopened.

Swiss Justice Ministry spokesman Folco Galli said the ministry had yet to receive the request.

Bhutto was killed in a December 2007 gun and suicide bomb attack, and Zardari was elected president in 2008. He took the office after his party forced military ruler Pervez Musharraf to resign.

He has struggled to make much of a dent in the country's myriad problems, but his government has been praised of late in the West for battling against the Taliban in the northwest.

The U.S. has pushed Islamabad to keep up its offensives, arguing that militants on its side of the border are involved in attacks on American and NATO troops in Afghanistan.

Earlier Wednesday, six soldiers and 20 Taliban militants were killed when troops repulsed an attack by dozens of insurgents on a checkpoint close to the Afghan border, a statement from Pakistan's paramilitary Frontier Corps.

Also Wednesday, at least six alleged insurgents were killed by suspected U.S. missiles in the nearby tribal region of North Waziristan, two Pakistani intelligence officials said.

Two missile attacks one hour apart destroyed an abandoned school near the town of Mir Ali, said the officials, who spoke on condition of anonymity because they were not authorized to speak to media.

The U.S. rarely discusses its missile campaign. Pakistan publicly protests it as a violation of its sovereignty, though it is believed to secretly assist in the strikes.

North Waziristan has been the target of the majority of recent missile attacks. It is home to several militant groups who focus on battling U.S. and NATO forces in Afghanistan.