Pakistan's embattled president has relinquished command of the country's nuclear arsenal in a first step toward formally reversing the emergency rule enjoyed by his predecessor.

The move came as President Asif Ali Zardari faces the expiration Saturday of an amnesty protecting him and thousands of other bureaucrats and politicians, threatening fresh political turmoil.

Zardari has come under pressure over past corruption allegations that he denies.

Zardari enjoys general immunity from prosecution as president, but the Supreme Court could choose to challenge his eligibility for the post since the amnesty decree by ex-military leader Pervez Musharraf was never formally approved by parliament.