He called it the deadliest attack this year.
Television footage showed scores of residents and police officers digging frantically with their hands through the ruins of the mosque after its roof collapsed in the explosion.
"These infidels had warned that they will take revenge"
Tariq Hayat Khan,
Khyber tribal region administrator
"The whole of the mosque collapsed and only two pillars remain. People were crying," Waheed Khan, a tribal policeman, said.
Rescuers carried bodies covered in dust and blood on blankets and scarves toward ambulances and private cars waiting to take them to hospital.
Tariq Hayat Khan, the most senior administrator in the Khyber region, told reporters the death toll could rise, perhaps to 70.
About 70 wounded had been taken to hospitals, he said.
"It was a suicide attack. The bomber was standing in the mosque. It's a two-storey building and it has collapsed," he said.
'Enemies of Pakistan'
Khan accused pro-Taliban fighters of carrying out the bombing after a recent offensive aimed in part at protecting a supply route for Nato and US troops operating in Afghanistan.
"Residents of this area had co-operated and helped us a lot. These infidels had warned that they will take revenge," Khan said.
"They are the enemy of Pakistan. They are the enemy of Islam."
Zeina Khodr, Al Jazeera's correspondent in Islamabad, said many of those killed were members of the security forces.
The mosque is near a police checkpoint and "people in that checkpoint usually pray in this mosque", she said.
"But the political agents are saying that, and I quote, 'no Muslim could carry out such a crime suggesting that foreign hands were responsible'."
Asif Ali Zardari, the president, and Yousuf Raza Gilani, the prime minister, both "strongly condemned the suicide attack" and vowed that the perpetrators would be brought to justice, government statements said.
Rising violence in Pakistan's northwest is fuelling doubts about the country's ability to counter pro-Taliban and al-Qaeda fighters blamed for attacks there, and across the border in neighbouring Afghanistan.