The Pakistani Taliban Wednesday said they would not extend a ceasefire called to help peace negotiations with the government, but insisted they were still committed to the talks process.

The Tehreek-e-Taliban Pakistan (TTP) announced a one-month ceasefire at the start of March as the government sought a negotiated end to their bloody seven-year insurgency.

The TTP extended the ceasefire to April 10, but complained there had been "complete silence" from the government since then and hinted that the military was trying to thwart talks.

"TTP's central shura (council) has unanimously agreed not to extend the ceasefire," the group said in a statement.

"However, the talks process will continue with complete sincerity and seriousness, and whenever a clear development comes from the government side, the TTP will not hesitate to respond with a serious move."

The announcement comes three days after Pakistan's Interior Minister Chaudhry Nisar Ali Khan said the process was about to enter a "comprehensive" phase.

Prime Minister Nawaz Sharif's government began negotiations with the TTP through intermediaries in February to try to end the Islamists' insurgency.

Since the TTP's fight began in 2007, more than 6,800 people have been killed in bomb and gun attacks around Pakistan, according to an AFP tally, destabilising the nuclear-armed state.

The umbrella militant group has demanded the release of what they call "non-combatant" prisoners and the establishment of a "peace zone" where security forces would not be present.

The government freed 19 tribesmen based in South Waziristan district last week and on Sunday Khan said 13 more of what he called "non-combatant Taliban" prisoners would be released to help the peace process.

South Waziristan is one of seven restive semi-autonomous areas along the Afghan border that are havens for the militants.

The TTP statement said there had been "no development" from the government on the militants' demands.

The government has also taken up the issue of the release of a senior academic -- Professor Mohammad Ajmal -- as well the sons of slain former Punjab governor Salman Taseer and former prime minister Yousaf Raza Gilani in return for its concessions to the TTP's demands.

- Scepticism -

Talks were a key campaign pledge for Sharif before he was elected to office for a third time last year.

But some analysts have voiced scepticism about their chances for success, given the Taliban's demands for nationwide sharia law and a withdrawal of troops from the lawless tribal zones.

Regional deals struck in the past between the military and the Taliban have failed and some have accused the militants of using them as a means to regroup and rearm.

Not all militant factions are signed up to the peace process -- a group calling itself Ahrar-ul-Hind claimed a major attack on an Islamabad courthouse just days after the ceasefire was originally announced.

Further evidence of discord within the militant ranks came last week with fierce clashes between rival TTP factions which left more than 60 people dead.