Il Nuovo Postiglione - Funerals for victims of suicide blast at Islamabad mosque that killed at least 31

The Islamic State group (IS) has claimed responsibility for the attack, the deadliest in Islamabad since the 2008 Marriott hotel bombing.

City officials said 31 people died and another 169 were wounded in the explosion at the Imam Bargah Qasr-e-Khadijatul Kubra mosque on the city's outskirts. The death toll was expected to rise.

The blast occurred during Friday prayers, when mosques are packed with worshippers.

"The attacker was stopped at the gate and detonated himself," a security source told AFP.

Muhammad Kazim, 52, said an "extremely powerful" explosion ripped through the building as prayers were just starting.

Another worshipper, Imran Mahmood, told AFP there was a gunfight between the bomber and volunteer security personnel at the mosque.

"The suicide attacker was trying to move forward, but one of our injured volunteers fired at him from behind, hitting him in the thigh," he told AFP.

He then "detonated the explosives", Mahmood added.

- Bodies, bloodied clothing, debris -

AFP journalists at a major hospital on Friday afternoon saw several people, including children, being carried in on stretchers or by their arms and legs.

Medics and bystanders helped unload victims with blood-soaked clothes from the back of ambulances and vehicles as friends and relatives of the wounded wept and screamed.

Heavily armed security forces guarded the mosque, where pools of blood were visible on the ground.

Videos shared on social media, which AFP was not able to immediately verify, showed several bodies lying near the mosque's front gate, with people and debris also strewn across the red-carpeted prayer hall.

Prime Minister Shehbaz Sharif vowed that those behind the blast would be found and brought to justice.

Deputy Prime Minister Ishaq Dar branded the attack "a heinous crime against humanity and a blatant violation of Islamic principles".

- Growing insurgencies -

The attack comes as Pakistan's security forces battle intensifying insurgencies in southern and northern provinces that border Afghanistan.

Pakistan is a Sunni-majority nation, but Shiites make up between 10 and 15 percent of the population and have been targeted in attacks throughout the region in the past.

The last major attack in Islamabad took place in November when a suicide blast outside a court killed 12 people and wounded dozens, the first such incident to hit the capital in nearly three years.

In Balochistan, attacks claimed by separatist insurgents last week killed 36 civilians and 22 security personnel, prompting a wave of counter-operations in which authorities said security forces killed almost 200 militants.

Friday's attack was the deadliest in the Pakistani capital since September 2008, when 60 people were killed in a suicide truck bomb blast that destroyed part of the five-star Marriott hotel.

E.Scozzafava--INP