LADDAH/ISLAMABAD, Oct 6 The Tehrik-i-Taliban Pakistan claimed on Tuesday it had carried out Monday's suicide attack on the main office of UN's World Food Programme in Islamabad and vowed further attacks on governments and foreign targets.

Five UN officials, four Pakistanis and an Iraqi among them, were killed when a suicide bomber dressed as a paramilitary soldier dodged strict security measures and detonated explosives in the heavily fortified office.

TTP spokesman Azam Tariq claimed responsibility and said his organisation would not leave the people of Pakistan at the mercy of the Blackwater security agency.

He said the Taliban were ready to face a military operation in the tribal region. Azam Tariq said Interior Minister Rehman Malik had refuted the fact that new TTP chief Hakeemullah Mehsud was alive. “He (interior minister) should visit South Waziristan and he would have a chance to meet Hakeemullah there,” he added.

Meanwhile,investigators have so far failed to identify the suicide bomber behind Monday's attack.

Interior Minister Rehman Malik rejected reports that the bomber was a serving or ex-member of the Frontier Constabulary. “Our strength is intact and complete and he (suicide bomber) was not an FC man,” he told reporters at his ministry on Tuesday.

But sources in security agencies said that senior investigation officers were trying to find evidence whether the bomber was an employee of the FC or not. They said that all heads of paramilitary forces, including FC, Rangers, Punjab Constabulary and AJK police whose 1,000 personnel were deployed at different places in Islamabad, had been called and asked to scrutinise their personnel.

The sources said the process of scrutiny or re-verification had been started to ascertain if the personnel of these forces had affiliation with any extremist or terrorist organisation.