The Pakistani Taliban have withdrawn their offer of peace talks, following the death of the group's deputy leader in US drone attack, a spokesman for the group said.
Hakimullah Mehsud, the leader of the Pakistani Taliban, had made the offer of talks to the government in December but imposed demanding conditions and said his men would never lay down their arms.
The announcement on Thursday was a blow to the incoming government of Nawaz Sharif that was elected partly on promises to restore security after years of deadly attacks.
The death of Wali ur Rehman, wanted by the US for a 2009 attack in Afghanistan that killed seven people working for the CIA, also focuses attention on the controversial US drone programme.
Despite President Barack Obama's sweeping promise last week of new transparency, Wednesday's strike against a longtime US target shows that the CIA will still launch attacks on fighters without having to explain them publicly.
The news came amid conflicting reports about whether the group had selected a replacement for Rehman, who was killed Wednesday in an attack that Pakistani officials said left at least four other fighters dead.
Taliban spokesman Ahsanullah Ahsan said the group is discussing whether Khan Said, Rehman's deputy, will succeed him as head of the group's most powerful branch in South Waziristan, which would effectively make him the second-in-command.
Two Taliban commanders said commanders voted in favour of Said at a meeting, but Ahsan said a vote had yet to be taken. The commanders both spoke on condition of anonymity because they were not authorised to speak to the media.
Said is believed to be about 40 years old and is known mainly for coordinating attacks in Afghanistan, say intelligence and Taliban sources.
He was responsible for organising an assault on a prison in northwestern Pakistan in April 2012 in which close to 400 prisoners, including 20 who were considered dangerous insurgents, were freed.
Ahsan also told the AP news agency in a telephone call from an undisclosed location that the group had withdrawn an offer to join peace talks because they believe the Pakistani government approves of the US drone strikes, despite official statements to the contrary.
He also formally confirmed that Rehman had been killed.
"We had made the offer for peace talks with the government with good intention but we think that these drone attacks are carried out with the approval of the government so we announce the end of the talks process," he said.
Three of the others killed were mid-level Pakistani aides to Rehman, two Pakistani intelligence officials said, also speaking on condition they not be identified because they were not authorised to release the information. They said they are still trying to confirm the nationality and identity of the fifth fighter.
The Pakistani Taliban, formed in late 2007, aims to overthrow the Pakistani government, which it believes is too closely aligned with the United States.
The group, formally called the Tehrik-e-Taliban or the TTP, has been responsible for hundreds of shootings and bombings across Pakistan that have resulted in thousands of deaths.
Earlier this year the group had indicated it was open to the idea of peace talks to end years of fighting if certain individuals, including Sharif, were involved.
The talks did not go anywhere at the time but the May 11 election victory of Sharif's party once again brought the issue to the forefront.
Days after the election Sharif, who is set to become prime minister for a third time, called for peace talks with the Taliban militants. Sharif said Taliban offers to talk should be taken seriously.
A spokesman for Sharif's party, the Pakistan Muslim League-N, promised to continue to push for talks when they take office despite the Pakistani Taliban's announcement.