UNITED NATIONS (AFP) – At Islamabad's request, the United Nations on Tuesday delayed the release of a sensitive report on the 2007 slaying of Pakistani ex-premier Benazir Bhutto as all UN offices in Pakistan were ordered temporarily closed as a security precaution.

"The Secretary General has accepted an urgent request by the President of Pakistan (Asif Ali Zardari) to delay the presentation of the report... until 15 April 2010," UN spokesman Martin Nesirky told a press briefing. He gave no further details as to the reason for the delay.

A UN-appointed independent panel, which began its investigations last July into Bhutto's December 2007 killing, had been due to submit its findings to UN chief Ban Ki-moon on Wednesday.

Nesirky said the report would not be shown to the Pakistani government before April 15. Ban himself had not yet read the document, he added.

He said that the commission informed Ban that "as of today, all relevant facts and circumstances have been explored, and the report is now complete and ready to be delivered."

Bhutto, the first woman to become prime minister of a Muslim country, was killed on December 27, 2007 in a gun and suicide attack after addressing an election rally in Rawalpindi, a garrison city near the capital Islamabad.

Her supporters cast doubt on an initial Pakistani probe into her death, questioning whether she was killed by a gunshot or the blast and criticizing authorities for hosing down the scene of the attack within minutes.

The delay was announced only two hours before the three-member inquiry commission was to give a press conference here on its findings. The press conference was also put off to mid-April.

The inquiry panel is headed by Chile's ambassador to the UN Heraldo Munoz and aided by Indonesian ex-attorney general Marzuki Darusman and Peter Fitzgerald, an Irish former police official.

The delay also came only hours after a UN spokeswoman in Islamabad said all UN offices in Pakistan would close for three days from Wednesday as a security precaution.

"It's a precautionary measure to avoid any unwanted situation that may occur after the publication of this report, for the safety and security of staff members," Ishrat Rizvi told AFP.

She added that staff are being advised to work from home in a bid to avoid any possible fallout.

The measure affects more than 2,000 staff in dozens of offices around the nuclear-armed country with a population of 167 million.

Rizvi later said UN staff in Islamabad were still unaware that the release of the report had been delayed.

"A new announcement has not yet come. Offices will remain closed tomorrow at least and we will then assess the situation," she noted.

On October 5, a suicide bomber clad in military uniform attacked the heavily fortified UN World Food Program office in Islamabad, killing five staff members.

Security is precarious in parts of Pakistan, where more than 3,150 people have been killed in suicide and bomb attacks over the last three years. The violence has been blamed on militants opposed to the government's US alliance.

Last February, the inquiry panel met Asif Ali Zardari, Bhutto's widower, ahead of finalizing its report.

It had also questioned former president Pervez Musharraf last November on issues central to its mandate.

Musharraf, who was in power at the time of Bhutto's death, was replaced in August 2008 as president by Zardari, whose party called for a UN inquiry to probe inconsistencies surrounding her killing.

But the inquiry commission team says its mandate is limited to fact-finding and does not include a criminal investigation.

London's Scotland Yard, which also conducted an inquiry, ruled that Bhutto died from the force of a suicide bomb and not gunfire.