ISLAMABAD: An amnesty on corruption cases protecting President Asif Ali Zardari, key allies and thousands of others formally expires on Saturday, threatening to fling Pakistan into fresh political crisis.

The National Reconciliation Ordinance, commonly known as NRO, was promulgated in October 2007 by military ruler Pervez Musharraf.

Musharraf's decree quashed corruption charges against former prime minister Benazir Bhutto, who was assassinated two months later, her husband Zardari and other politicians in an apparent gesture of reconciliation to prolong his rule.

Zardari's Pakistan People's Party won subsequent elections in February 2008, restoring civilian rule in a country that has been governed for most of its existence by the military.

Zardari has rock-bottom approval ratings as Pakistan struggles with Taliban violence, a recession and stalled efforts on reform.

He spent several years in jail for corruption and is still referred to as "Mr Ten Percent" because of his reputation for taking kickbacks on deals.

Weathering the worst political crisis of his rule so far, Zardari's government last March was forced to restore independent judges, who had been dismissed by Musharraf, after a nationwide protest.

On July 31, the new supreme court set a November 28 deadline for the NRO to be approved by the parliament or else it would lapse.

But the government is seen as too weak to win an extension. Last month the administration tabled the ordinance in parliament but quickly withdrew it after sensing political opposition was too strong.

"The NRO will lapse after November 28 and cases against beneficiaries will be deemed to be pending," senior lawyer Abid Hassan Minto told AFP.

"Cases can be reopened and convictions may be restored unless the government comes up with a separate order," he added.

Some analysts believe Zardari can stay in office only by agreeing to revoke Musharraf's 17th amendment to the constitution that gives the president the power to dissolve parliament and sack the prime minister.

"We wanted to abolish the 17th amendment from day one but we wanted to do it through unanimous decision, as the 1973 Constitution was also approved unanimously," Zardari said in interview given overnight to a private television channel, according to state run news agency, Associated Press of Pakistan.

"According to our legal team, the President has indemnity and its eligibility cannot be challenged now," the agency quoting the president as saying.

Zardari said his eligibility as president was not even challenged by his rival candidates at the time of the elections, the state run news agency reported.

"On November 28, nothing dramatic and unusual will happen. Life will move on," Farhatullah Babar, spokesman for Zardari, told AFP.

"The court will decide. We will cross that bridge when we come to it."

Last week, a minister of state published the names of 8,041 people who have benefited from the amnesty, including Zardari and some cabinet ministers.

The list is connected to 3,478 cases ranging from murder, embezzlement, abuse of power and write-offs of bank loans worth millions of dollars.

Interior Minister Rehman Malik and Defence Minister Ahmed Mukhtar were among more than 30 politicians who had cases withdrawn against them.

Analyst Talat Masood said the distraction posed by the president and ministers facing possible litigation would divert attention from the battle against Taliban fighters and suicide bombers.

"The opposition and other forces will continue pressure on the government to quit. Zardari will have to shed his powers to be able to survive," he told AFP.

Many lawyers argue that Zardari is immune from prosecution as president but political opponents say otherwise. Allies of the political opposition are also on the NRO list of beneficiaries.

"Another view is that no relief can be given against a crime, so the relief granted to him was illegal," said Siddiqul Farooq, spokesman for the Pakistan Muslim League-N (PML-N) led by popular opposition leader Nawaz Sharif.

"The court may declare it unconstitutional and his election illegal," PML-N spokesman Siddiqul Farooq told AFP.

"We are advising him to resign on moral grounds," he added, quoting the example of an adviser in the Punjab provincial government who has already stepped down after his name was published on the list of NRO beneficiaries.