Q+A: Who are Pakistani Taliban insurgents?

(Reuters) - A suicide car-bomber killed 10 people at a security checkpost in northwest Pakistan on Monday as the army battled Taliban militants in the Swat valley.

Surging violence and spreading Taliban influence have sent jitters across Pakistan and compounded Washington's worries about the stability of its nuclear-armed ally, vital for efforts to defeat al Qaeda and stabilize neighboring Afghanistan.

The offensive in Swat, 130 km (80 miles) northwest of Islamabad, is seen as test of the government's resolve to get to grips with the Taliban.

Here are a few facts about the Pakistani Taliban.

WHO ARE THE PAKISTANI TALIBAN?

Most Pakistani Taliban fighters are ethnic Pashtuns from northwestern regions on the Afghan border. They support the Afghan Taliban, most of whom are also Pashtun and many of whom fled to the Pakistani Pashtun lands after U.S.-led forces ousted Afghanistan's Taliban hardline Islamist government in late 2001.

Thirteen factions based in different parts of northwest Pakistan have formed a loose umbrella group, the Tehrik-e-Taliban Pakistan (TTP), or Taliban Movement of Pakistan, led by Baitullah Mehsud, based in South Waziristan on the Afghan border.

The United States in March announced a reward of $5 million for information leading to Mehsud's location or arrest.

Mehsud has been accused of being behind a wave of suicide attacks across Pakistan since the army stormed Islamabad's Red Mosque in July 2007 to crush a militant movement based there.

But it was when the government named Mehsud as the chief suspect in the assassination of former Prime Minister Benazir Bhutto, in a suicide attack in 2007, that Mehsud's notoriety rocketed.

The Taliban fighting in Swat are part of the TTP and are led by a commander called Fazlullah, the son-in-law of a pro-Taliban cleric who led thousands of tribesmen to Afghanistan to fight alongside Taliban after the U.S. invasion in 2001.

While many senior Taliban are veterans of Afghan fighting, they have exploited poverty, frustration over an ineffective judiciary, anger against landlords and widespread anti-U.S. feeling to attract recruits. Intelligence officials say they also press families to send sons to fight.

ARE THE PAKISTANI TALIBAN LINKED TO AL QAEDA?

Intelligence officials and security experts say Mehsud is an al Qaeda ally. He has given refuge to a large number of foreign militants, including Arabs and Central Asians, but the nature of his links with al Qaeda's leaders, believed to be hiding along the Afghan-Pakistani border, is not clear.

WHAT IS THE RELATIONSHIP WITH THE AFGHAN TALIBAN?

The TTP swears allegiance to Mullah Omar, chief of the Taliban in Afghanistan, and acknowledges sending fighters across the border to Afghanistan. The Afghan Taliban are fighting what they call Western "occupation" forces. Pakistani Taliban support that and also want their version of Islamist rule in Pakistan.

There are differences between the groups on whether to fight Pakistani security forces. Some oppose violence in Pakistan and want all Taliban to focus on Afghanistan. But leaders such as Mehsud and Fazlullah argue that fighting Pakistani forces is justified because of Pakistan's support for the U.S.-led campaign against al Qaeda and the Afghan Taliban.

Militant groups focused on fighting in Afghanistan recently set up the Ittehad-e-Shura-e-Mujahideen, or Union of the Consultative Council of Mujahideen, with the TTP. Analysts saw the move as aimed at forging unity in the face of a sharp build-up of U.S. forces in Afghanistan.

ANY LINKS WITH OTHER MILITANT GROUPS?

Intelligence officials say the Pakistani Taliban have also forged links with militants groups drawn from central Punjab province, giving the Taliban the ability to expand their influence out of the Pashtun-dominated northwest. One of these groups, the Lashkar-e-Jhangvi (LeJ), a Sunni Muslim militant group, is regarded as one of al Qaeda's main fronts in Pakistan.

(Reporting by Zeeshan Haider; Editing by Robert Birsel)