Pakistani police on Sunday arrested pro-Taliban cleric Sufi Muhammad, who brokered a peace deal between the government and militants in the Swat Valley that has since faltered.

Muhammad negotiated a truce with the government in February that imposed Shariah, or Islamic, law in Swat in exchange for an end to two years of fighting. But it was widely seen as an acquiescence to Taliban control of the valley.

The deal collapsed in April when the Taliban advanced into neighboring districts, triggering a military offensive that prompted a spree of retaliatory attacks by militants in the northwest and beyond.

Mian Iftikhar, information minister for the North West Frontier Province, said Muhammad was arrested for encouraging violence and terrorism.

"Instead of keeping his promises by taking steps for the sake of peace, and speaking out against terrorism, he did not utter a single word against terrorists," Iftikhar said in a news conference, adding that the cleric's stance "encouraged terrorism. It encouraged violence."

The military offensive in the Swat Valley and surrounding areas led some 2 million people to flee their homes and take refuge in camps and with relatives across the country. In the last two weeks, hundreds of thousands have been returning home as the offensive winds down, although sporadic fighting persists.

Iftikhar accused Muhammad of "again preparing to get more people killed" and said: "We cannot let it happen. The price we have paid for the sake of peace, we cannot allow any person to disturb the peace."

Iftikhar said Muhammad would be investigated regarding his role as mediator between the government and the Taliban, and that a case would then be made based on that investigation.

Muhammad's son Azmat Ullah, 12, told The Associated Press that police arrived at his home in Sethi on the outskirts of Peshawar in four vans and took away his father and three brothers.

"My father and brothers went with them without offering any resistance," Ullah said.

One witness, local resident Mohammad Arif, said police fired a shot in the air to disperse a crowd that had gathered during the operation to arrest the cleric.