Oct. 5 (Bloomberg) -- A suicide bomber in Pakistan killed five people in the UN World Food Program headquarters by dressing as a soldier and asking to use the toilet, officials said.

The attacker’s disguise concealed about 7 kilograms (15 pounds) of explosives, police said, and circumvented a two-story defensive wall the UN had built against car bombs. The assault underscored the vulnerability of Islamabad’s best-protected areas, raising a column of smoke over the upscale neighborhood where President Asif Ali Zardari has his home a few blocks away.

The attack was the deadliest in the Pakistani capital since April, and prompted a “temporary closure” of all United Nations offices in the country, WFP spokeswoman UN Ishrat Rizvi said. No decision has been made when to open them, she said.

Five people -- an Iraqi man and four Pakistanis, two of them women -- died by early evening, said Wasim Khawaja, spokesman for the Pakistan Institute of Medical Sciences hospital. WFP said earlier that four of its staffers were dead.

“This is a terrible tragedy for the UN and for the whole humanitarian community in Pakistan,” UN Secretary-General Ban KI-moon said in a statement released in New York.

“This is a heinous crime committed against those who have been working tirelessly to assist the poor and the vulnerable on the frontlines of hunger and other human suffering in Pakistan,” he said.

Foreign Targets

The bombing was the third in 16 months against foreign institutions in the capital, after attacks that killed 53 at the Marriott Hotel in September of last year and six at the Danish Embassy in June.

While no one claimed responsibility for the blast, Interior Minister Rehman Malik blamed Pakistan’s Taliban guerrilla movement, which has fought an escalated war this year against army troops in the country’s northwest.

“Five days ago there was a meeting of Taliban and they decided to attack cities and towns with suicide bombers,” he said. “There may be a few more attacks in the near future, but I assure you we will finish the remaining terrorists.”

The Taliban vowed to launch attacks to seek vengeance for the killing in August of its commander, Baitullah Mehsud, in a missile strike by U.S. unmanned aircraft. Pakistani troops are poised for a possible offensive against Mehsud’s fighters in South Waziristan, near the Afghan border.

The bomb exploded without warning about noon, said Saadia Abbasi, a Pakistani lawyer and former senator who lives across the street. “There was a terrible blast, and everything shook and smoke started pouring out” of the compound, she said in a telephone interview.

UN Food Aid

“The UN staff have brought about four or five people out of there, bleeding and injured,” Abbasi said

The UN agency has been providing food to many of the estimated 2 million Pakistanis uprooted by fighting in the Swat Valley and the Bajaur region of northwestern Pakistan this year.

The attack was the deadliest since April 4, when a suicide bomber attacked a paramilitary police post about 1 kilometer (0.6 miles) from the site of today’s blast, killing eight officers.

The attack will increase pressure on the UN and foreign embassies to move their offices in Islamabad out of the city’s elite residential neighborhoods to a fenced and guarded diplomatic enclave set up by the government. Rizvi said UN agencies are discussing such a move with Pakistani authorities and Malik said he has asked embassies to shift their facilities.

Bomb Defenses

Like many UN offices in Islamabad, the WFP headquarters is in a rented villa on a two-lane, residential street. After last year’s truck bomb attack that killed 53 people at the Marriott Hotel in the capital, WFP barricaded its office against vehicle bombs by building a two-story-high earth-filled barrier near the street.

Neighbors protested to the Pakistani government that the UN office represented a danger to the neighborhood because it could be targeted in an attack, said Abbasi. “There are four other UN offices in the same street, all surrounded by residences,” she said.

To contact the reporters on this story: Khalid Qayum in Islamabad at kqayum@bloomberg.net; James Rupert in New Delhi at 2024 or jrupert3@bloomberg.net.

Last Updated: October 5, 2009 10:52 EDT