A suicide bomber has struck a crowded mosque inside a police compound in Pakistan, causing the roof to collapse and killing at least 47 people and wounding more than 150 others, officials said.

Most of the casualties were police officers.

It was not clear how the bomber was able to slip into the walled compound, which houses the police headquarters in the north-western city of Peshawar and is itself located in a high-security zone with other government buildings.

Sarbakaf Mohmand, a commander for the Pakistani Taliban, claimed responsibility for the attack on Twitter.

The main spokesman for the militant group was not immediately available for comment.

Pakistan, which is mostly Sunni Muslim, has seen a surge in militant attacks since November, when the Pakistani Taliban ended their ceasefire with government forces.

Monday’s assault on a Sunni mosque was one of the deadliest attacks on security forces in recent years.

More than 300 worshippers were praying in the mosque, with more approaching, when the bomber set off his explosives vest.

Many were injured when the roof came down, according to Zafar Khan, a police officer, and rescuers had to remove mounds of debris to reach worshippers still trapped under the rubble.

Meena Gul, who was in the mosque when the bomb went off, said he does not know how he survived unhurt.

The 38-year-old police officer said he heard cries and screams after the blast.

Police official Siddique Khan said the death toll had risen to at least 47, while more than 150 people were wounded.

He said the bomber blew himself up while among the worshippers.

Peshawar police chief Ijaz Khan said at least 150 were wounded.

A nearby hospital listed many of the wounded in a critical condition, raising fears the death toll could rise.

Peshawar is the capital of Khyber Pakhtunkhwa province, where the Pakistani Taliban have a strong presence, and the city has been the scene of frequent militant attacks.

The militant group, also known as Tehreek-e-Taliban Pakistan or TTP, has waged an insurgency in Pakistan in the past 15 years.

It seeks the stricter enforcement of Islamic laws, the release of their members who are in government custody and a reduction in the Pakistani military presence in areas of Khyber Pakhtunkhwa province that it has longed used as its base.

The group is separate from but a close ally of the Afghan Taliban, who seized power in neighbouring Afghanistan in August 2021 as US and Nato troops pulled out of the country after 20 years of war.

The government’s truce with the TTP ended as Pakistan was still contending with unprecedented flooding that killed 1,739 people, destroyed more than two million homes, and at one point submerged as much as a third of the country.

Mohmand, of the militant organisation, said a fighter carried out the attack to avenge the killing of Abdul Wali, who was widely known as Omar Khalid Khurasani, and was killed in neighbouring Afghanistan’s Paktika province in August 2022.

Prime Minister Shahbaz Sharif condemned the bombing, vowed “stern action” against those behind it, and ordered authorities to give the best possible medical treatment for the victims.

Mr Sharif travelled to Peshawar and visited the wounded. His office said he would receive a briefing about the security situation in the north-west.

Former prime minister Imran Khan called the bombing a “terrorist suicide attack”.

He tweeted: “My prayers & condolences go to victims families. It is imperative we improve our intelligence gathering & properly equip our police forces to combat the growing threat of terrorism.”

Cash-strapped Pakistan faces a severe economic crisis and is seeking a crucial instalment of 1.1 billion dollars from the International Monetary Fund – part of its six billion dollar bailout package – to avoid default.

Talks with the IMF on reviving the bailout have stalled in the past months.

Mr Sharif’s government came to power in April after Mr Khan was ousted in a no-confidence vote in parliament. Mr Khan has since campaigned for early elections, claiming his ousting was illegal and part of a plot backed by the United States. Washington and Mr Sharif dismiss Mr Khan’s claims.