Karachi: Pakistan's commercial capital nearly shut down yesterday as religious and political leaders called for a strike to protest against violence after a suicide bomber killed 43 people at a religious procession this week.

The Taliban claimed responsibility for Monday's attack on a huge crowd of Shiites and threatened more bloodshed.

The prospect of increased violence comes at a trying time for President Asif Ali Zardari, who faces political heat because corruption charges against some of his aides may be revived.

The pro-American leader has vowed to defeat the Taliban and Al Qaida but they remain defiant, killing hundreds of people in bombings since October despite facing major government offensives.

In a sign of growing anxiety over security, the United Nations will withdraw some of its staff from Pakistan because of safety concerns, a UN spokeswoman said on Thursday.

On a visit to Karachi yesterday, Interior Minister Rehman Malik said militant groups were harming Pakistan, a country Washington needs to help stabilise neighbouring Afghanistan, where Western troops are battling a Taliban insurgency.

"They are hired assassins. They are enemies of Pakistan. They are enemies of Islam," he told reporters.

While many Pakistanis object to the violence, they are also frustrated with the government's inability to stabilise the nuclear power.

Militants have become increasingly brazen in their bid to topple the government and impose their brand of Islam, including public floggings and executions for anyone who disobeys them.

The Karachi carnage illustrated their reach is growing, from bastions on the Afghan border to cities, including an attack on a mosque near the headquarters of the powerful military.

Empty streets

Karachi's streets were nearly empty yesterday. The stock exchange, which normally operates on the first day of the year, was closed.

Police have arrested 18 people since riots triggered by the bombing destroyed hundreds of shops, costing Pakistan's biggest city an estimated 30 billion rupees (Dh2.3 billion) in damages.

Police and paramilitary forces carried out patrols. But residents were taking no chances.

"We are already losing business and can't take the risk of going out today and opening our shops," said Salim Ahmad, who sells electronics at one of the city's markets.

"If something happens or anyone comes and damages, say, one refrigerator or deep freezer, I will lose more money than what I would have earned the whole day, so I better stay home."

While investors in Pakistan have got used to almost daily attacks in the northwest, violence in Karachi has a much more direct impact on financial markets and investor sentiment.