The ruling council of the Pakistani Taliban is meeting to choose a successor to leader Hakimullah Mehsud, who was killed Friday in a US drone strike.

Here are some key facts about the organisation, its history, makeup and aims.

Who are the Pakistani Taliban?

The Tehreek-e-Taliban Pakistan (TTP) is an umbrella group for a nebulous collection of militant outfits, founded in December 2007 by Baitullah Mehsud, a warlord from South Waziristan tribal area.

Opposed to the 2001 US-led invasion of Afghanistan and supportive of Taliban who fled to Pakistan, the militants were galvanised by Pakistani military operations into their fiefdoms in the semi-autonomous tribal belt after 2002.

But it was a deadly military raid to clear the radical Red Mosque in Islamabad that prompted the creation of the TTP, which went on to become arguably the greatest national security threat to Pakistan.

What does the TTP want?

Bitterly opposed to the government's alliance with the United States in the war against the Taliban and Al-Qaeda, the TTP says its aim is to create an Islamic emirate in Pakistan, with sharia law, mirroring Afghan Taliban aims in Afghanistan.

Estimated to have at least 10,000 members, its ranks are drawn from Pashtun tribes in Pakistan's tribal belt.

The group dominates northwest Pakistan but it has penetrated central Punjab province and has a strong presence in parts of Karachi, the country's largest city.

More immediate demands from the TTP include the withdrawal of Pakistani troops from the tribal areas, the release of Taliban prisoners and the end of US drone strikes.

What major attacks have the TTP carried out?

The TTP has been behind hundreds of bomb and gun attacks that have fanned instability in Pakistan, killing more than 6,500 soldiers, police and civilians since 2007.

The government blamed Baitullah for the 2007 assassination of former prime minister Benazir Bhutto.

When Hakimullah Mehsud took over when Baitullah was killed in a US drone attack, he vowed revenge and the TTP dramatically stepped up attacks, exacting high civilian casualties and drawing comparisons with the nihilistic tactics of Al-Qaeda.

TTP's claim of involvement in a suicide attack carried out by a Jordanian Al-Qaeda agent that killed seven CIA employees in Afghanistan on December 2009 marked a departure for a group that had hithero concentrated its efforts in Pakistan.

Much of the TTP's campaign has been aimed at Pakistani security forces, including an attack on a naval base in Karachi in 2011 and another on Kamra air base in 2012.

They carried out two jailbreaks in Northwest Pakistan in April 2012 and in August 2013, releasing a total of 650 prisoners.

The group's international infamy soared in October last year when they sent gunmen to kill schoolgirl education activist Malala Yousafzai. She survived despite being shot in the head.