The Pakistani Taliban on Monday withdrew their offer of holding peace talks with the government, saying that the authorities were not serious about following through with negotiations.
The Taliban statement came as a pair of suicide bombers attacked a court complex in the north-western city of Peshawar.
One of the attackers was shot to death, but the other detonated his explosives in a packed courtroom, killing four people and wounding over 40 in the attack.
The Taliban have been waging a bloody insurgency against the government for over five years that has killed thousands of people.
The group first said it was open to negotiations at the end of last year in a letter sent to a local newspaper and a video released by Pakistani Taliban chief Hakimullah Mehsud.
Rehman Malik, who was interior minister until the government's term ended over the weekend, said in February that Islamabad was ready to hold peace talks, and appeared to drop an earlier demand that the Taliban lay down their weapons and renounce violence prior to negotiations - a position rejected by the militants.
Politicians from the country's main political parties also called for peace talks with the Taliban in February, at a meeting held in Islamabad to discuss the issue.
But Pakistani Taliban spokesperson Ahsanullah Ahsan said in a video sent to reporters on Monday that the group "has temporarily postponed the offer of negotiations" after a "non-serious response" by the government.
He accused the army of continuing its war against the Taliban in order to receive military aid from the US.
"Generals and politicians are sacrificing the country for their own interests," said Ahsan.
He called on Pakistanis to boycott upcoming national elections in May, saying Islamic law should be enforced instead.
"If this system is not rejected, the long, dark night of oppression will linger," said Ahsan.
He advised people to avoid rallies held by the Pakistan People's Party, which led the latest government, and by two other parties that have strongly opposed the militants, the Muttahida Qaumi Movement and the Awami National Party.
The Taliban's warning raises the worrying prospect of deadly violence in the run-up to the election.
A caretaker government is slated to take over and rule the country until elections are held.
The militants in Peshawar attacked the back of the court compound on Monday and were confronted by three police guards, said police officer Masood Afridi.
The militants shot and wounded the policemen, but not before one of the guards gunned down one of the suicide bombers.
The other bomber managed to get into the courtroom of a female judge and detonated his explosives, said Afridi.
Four people were killed and 47 wounded in the attack, said Habib Arif, a senior government official in Peshawar.
Twenty of the wounded were discharged from the hospital after receiving first aid, while 27 remain under treatment, said Arif.
The female judge presiding over the session inside the courtroom was among the wounded, said police officer, Mohammad Arshad Khan.
Naeem Ullah was standing outside the courtroom when the bomber blew himself up.
The blast "caused all of the glass in the windows to break, and I was wounded in my leg and back," said Ullah.
He spoke while receiving treatment at a local hospital.
The motive for the attack was not immediately clear.
The attackers may have been trying to free militant colleagues jailed on the premises of the compound, said Mian Iftikhar Hussain, the information minister for Khyber Pakhtunkhwa province, where Peshawar is the provincial capital.
Hussain initially suggested that the attackers may have taken some hostages, but later said the situation was under control.
Local TV footage showed people running for safety, including wounded people being assisted by others.
Police commandos and army soldiers rushed toward the complex, as the wounded were shifted to stretchers and taken to the hospital.
Peshawar is located on the border of Pakistan's semiautonomous tribal region, the main sanctuary for the Pakistani Taliban, who have carried out scores of bombings against the city.
No group claimed responsibility for Monday's attack.
In the southern port city of Karachi, paramilitary forces arrested a militant leader involved in the kidnapping and murder of Wall Street Journal reporter Daniel Pearl in 2002, said two paramilitary officials, speaking on condition of anonymity because they were not authorised to talk to the media.
Qari Abdul Hayee, a former leader of the Lashkar-e-Jhangvi militant group in southern Sindh province, was arrested on Sunday in Karachi, said the paramilitary officials.
He also went by the name Asadullah and was involved in other attacks in Karachi as well, they said.
Lashkar-e-Jhangvi is a radical Sunni Muslim militant group that has carried out many attacks in Pakistan, especially against minority Shi’ite Muslims.
Also in Karachi, gunmen riding on a motorcycle shot to death a Shi’ite professor, Sibt-e-Jafar, on Monday, said police officer Amir Farooqi.
No group claimed responsibility for the latest attack in Karachi.