ISLAMABAD (AFP) - Pakistan on Wednesday postponed general elections until February 18 following the assassination of opposition leader Benazir Bhutto, which sparked days of unrest that left dozens of people dead.

Bhutto's party and others have opposed the delay but with many election offices wrecked in the unrest that convulsed the nation after her killing, election officials said the delay was unavoidable.

"In the light of the circumstances, the new date for general elections is 18 February 2008 instead of January 8," chief election commissioner Qazi Mohammad Farooq told a news conference.

"I assure all political parties that the elections will be fair, free and transparent. I appeal to them to accept this decision in the supreme national interest and participate fully," he said.

The delay was announced hours before President Pervez Musharraf was to address the nation on state television, in a speech that officials said would appeal for unity and calm after Bhutto's killing at a campaign rally last week.

The election is seen as a crucial next step in the transition to civilian-led democratic rule in Pakistan under Musharraf, a close ally in the US-led "war on terror" who stepped down from his other post as army chief just weeks ago.

Senior officials had privately confirmed since Monday that the vote would be delayed, but the public announcement was delayed by talks with main political parties amid an uproar over the delay and the government response to Bhutto's death.

"President Musharraf will highlight the need for unity in the nation after the tragic death of Benazir Bhutto, and how terrorists are trying to undermine the country's security," a senior official who could not be named told AFP.

Her murder set off a wave of violence, arson and looting that has left 58 people dead and caused tens of millions of dollars in damage, including to dozens of election offices.

The loss of voter lists and the uncertain security situation delayed preparations for the vote, officials said.

Election commission spokesman Kanwar Dilshad said Tuesday that discussions had taken into account Moharram, one of the most sacred months in the Islamic calendar, which this year runs from around January 10 to February 8.

The United States, which counts Musharraf as a bulwark in the fight against Al-Qaeda and Taliban extremists, said a delay would be acceptable if the major political parties approved.

Bhutto's Pakistan People's Party, the country's largest, said Tuesday that any postponement was "an excuse to buy time" for Musharraf's allies "to come up with means to rig polls to turn the results in their favour."

Every recent election in Pakistan, the world's only nuclear-armed Islamic nation, has been marred by allegations of fraud.

Opposition parties have charged that the election commission has been stacked with Musharraf supporters, and that the interim government named to run the country in the run-up to the election is also pro-Musharraf.

Bhutto returned home from eight years of exile in October to contest the election, which will determine the make-up of parliament as well as that of assemblies in Pakistan's four provinces.