ISLAMABAD - The United Nations will withdraw some of its staff from Pakistan because of safety concerns, a U.N. spokeswoman said on Thursday, highlighting security threats posed by increasingly brazen Taliban militants.

Some percentage of the international staff will be relocated and this relocation includes within the country and outside the country to safer locations, Ishrat Rizvi told Reuters.

Despite military crackdowns, Taliban militants have been carrying out bombings that have spread from their strongholds along a lawless northwest tribal belt to major cities, including one attack near the headquarters of the powerful military.

Rizvi said the relocation was decided because the safety and security situation in the country and safety of staff members is highly important for the United Nations.

In October, a suicide bomber dressed as a paramilitary soldier blew himself up in an office of the U.N. World Food Programme (WFP) in Islamabad, killing five staff members.

The Taliban, who reject any ties with Western powers and want to impose their radical version of Islam, claimed responsibility for a suicide bombing that killed 43 people in the commercial capital of Karachi on Monday and sparked riots.

Pakistan is facing its most challenging time for the last few years. In light of this, the Secretary General decided to realign the projects and programmes of the United Nations in Pakistan, said Rizvi.

Aside from its struggle against the Taliban and al Qaeda on the ground, Pakistan, like other countries, faces the new challenge of breaking militant networks on the Internet, where readily available videos encourage people to blow themselves up.

Pakistani police will ask a court to charge five Americans detained in the country this month with planning terrorist attacks and imprison them for life, a police official said.

The young Americans, from Virginia, are accused of contacting militants groups over the Internet in a bid to wage holy war.

Pakistani officials have said the Taliban had planned to use them to carry out attacks inside U.S. ally Pakistan.

Pakistan's lawless areas bordering Afghanistan are known sanctuaries for al Qaeda and Taliban militants who fled the U.S.-led assault on Afghanistan after the Sept. 11, 2001 attacks on United States.

Washington wants Islamabad to crush militants who cross over to Afghanistan to attack U.S.- and NATO-led troops fighting a raging Taliban insurgency. Pakistani President Asif Ali Zardari has vowed to defeat Taliban insurgents.

But Zardari is deeply unpopular and it is the all-powerful powerful military, which rejects any attempt by Washington to influence Pakistan's affairs, that decides security policy.

The army is focusing on fighting homegrown Taliban militants. And rooting out militants along the border could be a strategic mistake. The army sees them as leverage against traditional enemy India in Afghanistan so its resists U.S. pressure to crack down.

The U.N. decision comes at a time of anti-American feelings in Pakistan. Pilotless U.S. drone attacks on militant targets on Pakistani soil and a U.S. aid package with conditions many see as a violation of sovereignty have infuriated Pakistanis.
Endless conspiracy theories about alleged U.S. designs Pakistan may make U.N. officials in Pakistan nervous. Some newspapers have suggested American security contractors are carrying out clandestine missions that harm the country.

Emails showed that the five detained Americans had plans to travel to a Pakistani nuclear power plant, according to police.

The men -- two are of Pakistani ancestry, one of Egyptian, one of Yemeni and one of Eritrean -- were arrested in Sargodha, home to one of Pakistan's biggest airbases, 190 km (120 miles) southeast of the capital Islamabad.

(For more Reuters coverage of Afghanistan and Pakistan, see:here) (Writing by Michael Georgy; Editing by Alex Richardson)