A religious leader who negotiated an agreement that ended fighting between the Taliban and security forces in Pakistan's Swat valley has said he is pulling out of peace talks.

Sufi Muhammad said on Thursday he was withdrawing because the government had been too slow to introduce sharia (Islamic law) in the region.

He has left the Swat valley to set up a protest camp at his old headquarters in Malakand province.

His statement calls into question the durability of a controversial peace effort in the valley, where fighting has forced thousands of residents to flee.

Asif Ali Zardari, Pakistan's president, has said he will sign an order introducing
sharia in the region only once peace has been fully restored.

Government blamed

Al Jazeera's Kamal Hyder, reporting from Islamabad, said: "Sufi Muhammad, who was the key factor in brokering a peace deal in the Swat valley ...  has blamed the central government directly for dragging their feet on the accord.

"All this is happening at a time when the Swat Taliban has moved into an adjoining district and are saying that they cannot be stopped from going into other areas.

"That is going to be a very serious development and, if that peace accord does break down, it will have serious repercussions for the adjoining districts as well."

Also on Thursday, Mullah Nezaar, a Pakistani Taliban leader, released an audio message on the internet, claiming that his group is just days away from marching on the capital.

"Pakistan Taliban factions have united ... The day is not far when Islamabad will be in the hands of the mujahidin."

He also accused the Pakistan army of using spies to help the US carry out unmanned drone attacks on rural areas of Pakistan.