ISLAMABAD - Pakistan has ordered the military to carry out an offensive against Pakistani Taliban leader Baitullah Mehsud and his fighters, a provincial governor said on Sunday.

The announcement came hours after a bomb in a market killed eight people in a northwest Pakistani town, the latest in a wave of attacks since the army launched an offensive against Taliban militants in the Swat valley northwest of Islamabad.

Nuclear-armed Pakistan is struggling to push back a growing Taliban insurgency and security forces have made progress in more than a month of fighting against militants in Swat.

The militants have responded with a string of bombs in towns and cities.

Mehsud has been blamed for many of the suicide attacks in Pakistan, including the assassination of former prime minister Benazir Bhutto, in December 2007.

Expectations have been rising that the military will launch an offensive against him as the army enters the final stages of its campaign in Swat.

The military and law enforcement agencies have been ordered to carry out a full-fledged operation to eliminate these beasts and killers by using all resources, Awais Ahmed Ghani, governor of North West Frontier Province, told reporters, referring to Mehsud.

He did not say when the offensive would be launched but said Mehsud and his people had provided shelter to anti-Pakistan forces, including many foreigners, and had been training suicide bombers.

The violence has raised fears for Pakistan's stability and for the safety of its nuclear arsenal but the offensive in Swat has reassured the United States, which needs its Muslim ally's help to defeat al Qaeda and stabilize neighboring Afghanistan.

DRONE STRIKE

Earlier on Sunday, a bomb planted on a cart in a market in the northwestern town of Dera Ismail Khan killed eight people and wounded 25, a government official said.

Separately, a suspected U.S. drone aircraft fired a missile in South Waziristan killing three militants traveling in a vehicle, a witness and officials said.

A government official in the region confirmed the attack, saying drones had been flying over South Waziristan since early morning. The identity of the dead militants was not known.

The United States, alarmed by the deteriorating security in Afghanistan, has also been using drone aircraft to attack Taliban and al Qaeda fighters in northwestern Pakistani militant strongholds.

Though a staunch U.S. ally, Pakistan objects to the U.S. missile strikes saying they violate its sovereignty and undermine efforts to deal with militancy because they inflame public anger and bolster militant support.

WARPLANES

Aircraft struck another Mehsud stronghold in South Waziristan on Saturday in retaliation for the killing of an anti-Taliban cleric in a suicide attack in the city of Lahore the previous day. The strike killed 30 militants, including a few foreigners, and wounded 50, the military said on Sunday.

Independent casualty estimates were not available.

In the past week, the military has stepped up attacks in several parts of the northwest in what analysts see as an attempt to distract the militants and soften up their positions.

Residents in the Bajaur region on the Afghan border to the northeast of Waziristan said aircraft bombed militants in several villages on Sunday but there were no reports of casualties.

The fighting in Swat and other parts of the northwest has displaced about 2.5 million people and aid officials have appealed to donors to step up their help.

The public largely backs the government in its war on the Taliban but support could evaporate if civilians are seen to suffer unduly.

On Thursday, the U.S. House of Representatives approved tripling aid to Pakistan to about $1.5 billion a year for five years to help combat extremism through development. Pakistan is now the biggest recipient of U.S. aid.

(Reporting by Javed Hussain, Alamgir Bitani and Sahibzada Bahauddin; Writing by Robert Birsel)