Pakistani opposition leader Nawaz Sharif was barred Monday from running in crucial forthcoming parliamentary elections due to a criminal conviction following his ouster as prime minister eight years ago.

Election officials in the eastern city of Lahore, Sharif's home base and political stronghold, rejected his nomination papers for the January 8 polls because of his convictions in 2000 on hijacking charges. The conviction stemmed from Sharif's refusal to allow an inbound commercial airliner carrying then-Army chief General Pervez Musharraf to land in Islamabad in October 1999 during a domestic political struggle.

The Pakistan International Airlines plane, coming from Sri Lanka, eventually landed after Army troops loyal to Musharraf took over the airport and later the government, completing a bloodless coup that has kept him in power ever since.

"Mr Nawaz Sharif was convicted in the airplane conspiracy case, so he cannot run in the elections," said Raja Qamaruzzaman, an election official in Lahore.

Sharif was later pardoned in the hijacking case, as well as for subsequent treason and corruption convictions, and returned home from exile in Saudi Arabia on November 25 to contest the polls. But he has since been trying to rally fellow opposition leaders into boycotting the elections to isolate his bitter rival Musharraf, who last week was sworn in to a new five-year term as Pakistan's president.

Musharraf declared a state of emergency on November 3 amid fears the country's Supreme Court was going to nullify his October re-election win. He jailed political opponents and judges, banned public rallies and placed curbs on the domestic media.

A defiant Sharif said he would not be deterred by the ruling on his nomination, which analysts had speculated could happen given his feud with Musharraf.

"I don't care if my nomination papers are even rejected 100 times. My struggle is not to come into power, but my struggle is for the rights of the Pakistani people," he told reporters in Islamabad.

Sharif was scheduled to meet opposition leader Benazir Bhutto on Monday night in Islamabad in hopes of convincing her Pakistan People's Party (PPP), the country's largest, to join an alliance of more than 30 other parties against Musharraf, who has refused to lift the emergency measures until at least mid-December.

But Bhutto, another former prime minister who returned from self-exile in October under an amnesty agreement with Musharraf, has been hedging her bets. While saying the PPP reserved the right to withdraw from the polls if it appeared they were being rigged, Bhutto has unveiled her party's election manifesto and began campaigning in earnest during the weekend in the country's volatile north-west region.

Sharif flew to Islamabad from Lahore on Monday afternoon for the first time since returning from exile, and was greeted by hundreds of cheering supporters who lined streets leading to the airport to watch his motorcade drive into town. A short time later, local television stations began reported that he had been barred from the election.

Pakistani law prohibits convicted felons from running for public office. The nominating papers of Shahbaz Sharif, the opposition leader's brother, were also rejected Monday because of a separate legal case.

Anne W Patterson, the US ambassador to Pakistan, has urged the government to release jailed opposition figures and allow all parties to participate in the elections. Visiting Turkish President Abdullah Gul was meeting with opposition figures on Monday and has urged them to "look at the big picture" concerning Pakistan's current crisis.