RAWALPINDI, Pakistan: An explosion outside a bank near Pakistan's capital killed at least 20 people Monday, the latest in a wave of attacks by militants since the army launched a new offensive against them last month.

The growing violence in the country prompted the UN on Monday to suspend long-term development in Pakistan's volatile northwest, complicating international efforts to counter the allure of Islamic extremism by improving people's lives.

Monday's explosion in Rawalpindi, located only a few miles (kilometers) from Islamabad, left bodies on the ground outside the bank and in the parking lot of a nearby hotel, said witness Zahid Dara.

"I was nearby and rushed toward the parking area," Dara told Dunya television. "There were many people lying on the ground with bleeding wounds, and a motorcycle was on fire with one man under it."

"The bodies were lying all over," Babar told The Associated Press. "This is a terrible thing. It is happening again and again."

Foreign Minister Makhdoom Shah Mahmood Qureshi condemned the blast, saying in a statement that "such barbaric, inhuman and un-Islamic terrorist acts only strengthen our resolve to fight terrorism with more vitality."

Militants killed some 250 people in attacks in October, but the government has vowed to continue the military offensive it launched last month against Taliban and al-Qaida fighters in their tribal stronghold of South Waziristan along the border with Afghanistan.

The US has urged the Pakistani government to persevere with the offensive against the militants, who have used the border region as a sanctuary to launch attacks against coalition forces in Afghanistan.

Washington has also stepped up its efforts to use development aid to battle the militants, hoping improvements in people's lives will reduce the allure of Islamic extremism. The US government recently approved $7.5 billion in aid over five years to improve Pakistan's economy, education and other non-military sectors.

But the UN's decision to suspend long-term development work in Pakistan's tribal areas and North West Frontier Province could complicate Washington's goal. The Pakistani military has launched offensives in both areas to defeat militants, but analysts have warned the gains could be short-lived if the operations aren't followed by economic development.

The UN made its decision after losing 11 of its personnel in attacks in Pakistan this year, including last month's bombing of the World Food Program's office in Islamabad that killed five people.

UN workers were also among the 11 killed in a June suicide bombing of the Pearl Continental Hotel in the main northwest city of Peshawar, and a veteran UN official was shot dead along with a guard while resisting kidnappers at a northwest Pakistan refugee camp in July.

The UN will reduce the level of international staff in the country and confine its work to emergency, humanitarian relief, and security operations, and also "any other essential operations as advised by the secretary-general," the organization said in a statement.

The UN has been deeply involved in helping Pakistan deal with refugee crises that have popped up due to army offensives against militants in the northwest.

UN spokeswoman Amena Kamaal told The Associated Press that the organization is still determining which programs will be suspended and how many staffers will be withdrawn from the country. The staff that remains in the country will be assigned additional security, she said.

"We have had 11 of our colleagues killed because of the security situation," said Kamaal. "All of the decisions are being made in light of that."

Foreign Ministry spokesman Abdul Basit said he hoped the UN would continue its development work after the military completed its operation in South Waziristan.

"We hope that our operation will come to an end soon and they will resume their normal operations," he said.