(Adds context, government negotiator)
By Katharine Houreld and Mehreen Zahra-Malik
ISLAMABAD, March 1 (Reuters) - The Pakistani Taliban on Saturday announced a one-month ceasefire aimed at reviving peace talks after receiving what it said were government assurances it would not be attacked.
A government negotiator could not confirm that there were such guarantees, but said talks could be restarted if the ceasefire was honored.
Speculation has mounted in recent weeks that the Pakistani military is planning an offensive against the insurgents after talks between the militants and government broke down.
"The senior leadership of the Taliban advises all subgroups to respect the Taliban's call for a ceasefire and abide by it and completely refrain from all jihadi activities in this time period," spokesman Shahidullah Shahid said in a statement.
Peace talks between the Pakistani government and Taliban insurgents began on Feb. 6 but broke down after insurgents said they executed 23 men from a government paramilitary force in revenge for the killing of their fighters by army forces.
The Pakistani Taliban is fighting to topple Prime Minister Nawaz Sharif's democratically elected government and impose Sharia law in the nuclear-armed nation.
Attacks have been on the rise since Sharif came to power in May, promising a negotiated end to violence. His stance unnerved global powers already worried that withdrawal of most U.S.-led troops from Afghanistan in 2014 would leave a security vacuum.
Senior Taliban officials told Reuters that they announced the ceasefire after receiving assurances from the civilian government that they would not be attacked.
"Senior officials of the federal government promised us the government and its law-enforcement agencies would not take any action against our people in the country," a senior Taliban commander said. "You can say the government first announced ceasefire and we did it later."
He declined to say who in the government made the guarantee.
Spokesman Shahid confirmed that the Taliban shura agreed unanimously on the ceasefire after receiving government promises.
Irfan Siddiqui, a government negotiator, said the government team would meet early next week to discuss the ceasefire and potentially restarting peace talks.
"If they are able to implement the ceasefire effectively and control the other groups, I think we could restart (talks)," he said. "It is a positive development."
Imtiaz Gul, the head of Islamabad-based thinktank the Center for Research and Security Studies, said the Taliban appeared to be wary of more military operations but doubted they had changed their objectives of overthrowing the state.
"It seems to be a tactical move in view of the losses they have been taking," he said. "The message from the army has been very clear, they will not accept any nonsense."
The Pakistan air force has launched sporadic raids against what it describes as militant targets in the northwest since the talks foundered.
A military spokesman has said dozens of militants were killed but the area is off limits to journalists so death tolls are impossible to independently verify.
Media, analysts and politicians have speculated the army is planning an offensive in North Waziristan, a tribal region bordering Afghanistan.
The United States has long pressed for such an offensive, which it says will help dismantle safe havens for fighters that attack its troops in Afghanistan.
The Afghan and Pakistani Taliban are allied but have different targets. The Afghans attack Afghan government and NATO forces, and the Pakistani Taliban concentrate on attacks against Pakistani government and military forces.
The Pakistani military did not respond to requests for comment. (Additional reporting by Jibran Ahmad in Peshawar and Saud Mehsud in Dera Ismail Khan; Writing by Katharine Houreld; Editing by Sonya Hepinstall)