The Pakistani Taliban has formally ended a 40-day ceasefire but is still open to talks with the government, according to a spokesman for the group.
Shahidullah Shahid said the Pakistani Taliban was not extending the ceasefire , which began on March 1, because the government had continued to arrest people and had killed more than 50 people associated with the group.
"However, the talks will continue with sincerity and seriousness and in case there is clear progress from the government side, [the Taliban] will not hesitate to take a serious step," he said in a statement.
The announcement comes three days after Chaudhry Nisar Ali Khan, Pakistan's interior minister, said the process was about to enter a "comprehensive" phase.
Peace talks between the Taliban and the government of Nawaz Sharif began in February but the first round ended in violence.
The Pakistani government has released a few low-level non-combatant prisoners, but the Taliban want hundreds of men released and the army to pull back from tribal areas bordering Afghanistan.
South Waziristan is one of seven semi-autonomous areas along the Afghan border that are havens for the fighters.
Talks were a key campaign pledge for Sharif before he was elected to the prime minister's office for a third time last year.
But some analysts have voiced scepticism about their chances for success, given the Pakistani Taliban's demands for nationwide Islamic law and a withdrawal of troops from the lawless tribal zones.