Four dead as suicide blast hits UN Islamabad office

A suicide bomber dressed in military uniform struck inside a heavily fortified UN office in the Pakistani capital Islamabad on Monday, killing three Pakistanis and an Iraqi working for the food agency.

Police said they were investigating how the bomber managed to breach strict security measures and walk into the offices of the World Food Programme (WFP) and detonate about eight kilograms (17 pounds) of explosives.

There was no claim of responsibility, but blame immediately fell on the Taliban, amid an upsurge of suicide bombings as the new leadership vow to avenge the death of their commander Baitullah Mehsud in a US missile strike.

"Four people have been martyred -- one of them is an Iraqi national," Interior Minister Rehman Malik said, adding that six Pakistanis were injured.

"They (Taliban militants) have prepared a strategy and there is the possibility of more such incidents in the near future," he told reporters.

There were scenes of confusion around the WFP compound in central Islamabad, with sirens blaring and smoke billowing from behind the blast walls. Injured survivors walked amid shattered glass and blood-slicked floors.

"We were on the upper storey when the blast took place. It shook the building and shattered the windows," said one WFP employee at the scene.

"We saw smoke coming out of the building, we rushed out. The blast was in the lobby on the ground floor."

UN offices across Pakistan have been closed until further notice over security concerns, United Nations spokeswoman Susan Manuel told AFP.

Bani Amin, deputy inspector general of police operations, said the explosion was caused by a suicide bomber who entered the building on foot, killing two Pakistani women, one Pakistani man and an Iraqi man.

"We have recovered legs and the skull of the suicide bomber. We are investigating how he managed to enter the building. There are scanners, there are cameras and strict security arrangements," Amin said.

The WFP confirmed in a statement from its Rome headquarters that four of its staff members had died in the blast.

"All of the victims were humanitarian heroes working on the frontlines of hunger," said WFP executive director Josette Sheeran. "This is a tragedy not just for WFP but for the whole humanitarian community and for the hungry."

UN Secretary General Ban Ki-moon called the attack a "heinous crime."

Interior minister Malik said that the bomber was dressed in the uniform of the paramilitary Frontier Corps -- who guard the WFP offices -- and asked to use the toilet before detonating his explosives.

Malik blamed the Taliban and said they were avenging an offensive against them which the military launched in April in northwest Swat valley, with the army now poised to begin a similar assault in the lawless tribal belt.

"This has broken their back, they are behaving like a wounded animal," Malik told reporters.

Taliban militants holed up in the northwest tribal belt have been blamed for a string of attacks and suicide blasts that have killed more than 2,100 people in the last two years, with 12 blasts hitting Islamabad alone.

Three bomb blasts in the past two-and-a-half weeks in the northwest have killed 28 people, with the Taliban claiming responsibility for one of the blasts and threatening to unleash bigger assaults.

There was a lull in bomb attacks after Baitullah Mehsud's death in an August 5 US drone strike, but analysts had warned that the new Taliban leadership would likely be keen to show their strength with fresh, dramatic strikes.

It is the second tragedy to hit the UN community here this year, with an employee from refugee agency UNHCR and another from children's agency UNICEF killed in a June suicide blast at a luxury hotel in northwest city Peshawar.

The Islamabad blast came as two senior British ministers -- Home Secretary Alan Johnson and Defence Secretary Bob Ainsworth -- were in the capital for talks on countering the insurgents.