"These officials, in part fearing intelligence agencies' involvement, were unsure of how vigorously they ought to pursue actions, which they knew, as professionals, they should have taken," it added.

Farhatullah Babar, a spokesman for Bhutto's Pakistan People's Party, said the findings of the UN report were in line with the party's own views on the killing.

"It is quite obvious that the suicide bomber did not act alone," he told Al Jazeera.

He said the party would be issuing a detailed comment on the report once it had studied the document in detail.

'Profound failures'

Munoz cited specific failures such as the hosing down of the crime scene within just hours of her killing, destroying potentially vital forensic evidence.

The report noted that responsibility for Bhutto's security on the day of her assassination rested with "the federal government, the government of Punjab and the Rawalpindi district police."

UN Bhutto report: Key points

 Pakistani police deliberately failed to thoroughly investigate Bhutto's death.

 Crime scene was hosed down within hours of her killing.

 Security measures taken to protect the former PM had been "fatally insufficient".

 UN panel said its own investigation was also "severely hampered" by Pakistani intelligence agencies.

Read the full UN report (pdf)

"None of these entities took the necessary measures to respond to the extraordinary, fresh, urgent security risks that they knew she faced," it said.

In addition the report said the Pakistani government had failed to provide Bhutto with the same stringent and specific security measures it had ordered for two other former prime ministers who belonged to the main political party backing then president Pervez Musharraf.

"This discriminatory treatment is profoundly troubling given the devastating attempt on her life only three days earlier and the specific threats against her which were being tracked" by Pakistani intelligence.

Al Jazeera's Kristin Saloomey, reporting from the UN, said the report was likely to have "serious repercussions" for the Pakistani government.

She said Pakistan's ambassador Abdullah Hussain Haroon had cancelled a scheduled media briefing immediately after the release of the report.

The report's allegations that some Pakistanis officials "severely hampered" the UN investigators work will cause unease in Islamabad.

"The commission was mystified by the efforts of certain high-ranking Pakistani government authorities to obstruct access to military and intelligence sources,"the report's authors said, although they noted that many other officials had offered full cooperation.

Explosion

Bhutto, Pakistan's first and to date only female leader, was killed on December 27, 2007 in a gun and suicide attack after addressing an election rally held by her Pakistan People's Party in Rawalpindi, a garrison city near the capital Islamabad.

In depth

Benazir Bhutto

  Focus: Bhutto's disappearing legacy

Video footage showed a gunman firing toward her vehicle as she left the rally, following which an explosion took place.

Bhutto had written in her autobiography of warnings that four suicide squads - including one sent by a son of Osama bin Laden, the leader of al-Qaeda - were after her.

She also repeatedly accused a cabal of senior Pakistani intelligence and government officials of plotting to kill her, notably in an attack that killed 139 people in Karachi on October 18, 2007 when she returned from exile.

'Ineffective'

The UN panel, which interviewed more than 250 figures during their investigation, was tasked with establishing the facts and circumstances surrounding Bhutto's killing and was not empowered to identify culprits.

Al Jazeera's Kamal Hyder, reporting from Rawalpindi, said the report raised big question marks over the actions of Pakistani authorities.

Bhutto was the first woman to become prime minister of a Muslim country [AFP]

"Obviously this will have ramifications throughout Pakistan," he said.

In its report, the UN panel said the Pakistani investigation into Bhutto's killing had "lacked direction, was ineffective and suffered from a lack of commitment to identify and bring all of the perpetrators to justice."

It called on the Pakistani authorities to carry out a "serious, credible criminal investigation that determines who conceived, ordered and executed this heinous crime… and brings those responsible to justice."

The UN report had been due for release at the end of March, but was delayed by two weeks at Pakistan's request.

Pakistani officials said last week that they had asked for the delay so that input from Afghanistan, the United States and Saudi Arabia could be included.

Rehman Malik, Pakistan's interior minister, said he had asked the panel to include input from Condoleezza Rice, the former US secretary of state, Hamid Karzai, the president of Afghanistan, and Saudi Arabia in its report.

He did not elaborate further on what information he wanted to be included.