Peshawar: The death toll in a militant attack on a mosque in northwest Pakistan rose to 22 on Saturday after another injured person died of his wounds, officials said.

Three heavily armed Taliban militants stormed the Imamia mosque with grenades, Kalashnikovs and explosive suicide vests in Peshawar, the main city in Pakistan’s restive northwest, around the time of the main Friday prayers.

“Another injured person, Ali Hassan, has succumbed to his injuries in the hospital, raising the death toll to 22,” Hayatabad Medical Complex official Tqauheed Zulfiqar told AFP.

Hassan’s father, Kalb-e-Hassan, was also killed in Friday’s attack.

“Around 41 injured people are still under treatment in different hospitals,” Peshawar’s Lady Reading Hospital said in a statement.

The attack came two weeks after a suicide bombing at a mosque in southern Pakistan killed 61 people, the deadliest sectarian incident to hit the country in nearly two years.

The Tehreek-e-Taliban Pakistan (TTP) claimed responsibility for Friday’s attack in an email statement, saying it was revenge for a militant known as Doctor Usman, who was hanged in December.

Since June last year the army has been waging a major campaign against strongholds of TTP and other militants in the North Waziristan tribal area, which lies close to Peshawar.

The military has heralded the success of the operation, which it says has killed more than 2,000 militants, though the precise number and identity of those killed cannot be verified independently.

The country has stepped up its fight against militants since Taliban gunmen massacred more than 150 people, most of them children, at a school in Peshawar in December.

Following the massacre, Prime Minister Nawaz Sharif ended a six-year moratorium on the death penalty and Doctor Usman, also known as Aqil, was one of the first to go to the gallows.

He was convicted for an attack on the army headquarters in Rawalpindi in 2009 and was arrested after being injured.

Anti-Shiite attacks have been increasing in recent years in Karachi, Quetta, the northwestern area of Parachinar and the far-northeastern town of Gilgit.