Quetta, Pakistan: A suicide bomber blew himself up outside a polio vaccination centre in the southwestern Pakistani city of Quetta on Wednesday, killing at least 15 people, officials said, in a Taliban-claimed attack.

The victims, mainly policemen, had been gathering outside the centre to accompany polio workers on the third day of a vaccination campaign which has been frequently targeted by Taliban and other Islamist militant groups in Pakistan.

Quetta is the capital of the restive Balochistan province, which is also home to a separatist insurgency that has been raging since 2004.

‘There are 15 dead, including 12 police, one paramilitary, and two civilians,’ a local police official told AFP.

Sarfraz Bugti, Balochistan home minister added: ‘So far 15 people have been injured in the blast, seven of whom are in critical condition.’ 

An AFP reporter at the site saw three burned out vehicles that had been blown up in the explosion, while human remains lay strewn across the area, along with items of clothing including the caps and shoes of policemen.

Some officials had begun to gather evidence from the scene while others were collecting body parts.

Eye-witness Shabir Ahmed, a 32-year-old police constable, told AFP he had been deployed to protect a polio vaccination team that was due to leave for various neighbourhoods of Quetta at 10 am.

‘Suddenly there was a loud bang and I fell to the ground, I could not see anything, there was dust everywhere,’ he said.

‘Then I heard people screaming and sirens of ambulances,’ he continued, adding he had received shrapnel wounds to his stomach, hands, legs and feet.

Anwar ul Haq Kakar, a spokesman for the provincial government, vowed the polio immunisation drive would continue.

‘We won't allow the nefarious designs of the terrorists to succeed, we will eliminate polio,’ he said.

The attack was later claimed by the Pakistani Taliban, who have been waging an insurgency against the government since 2007.

‘We accept the responsibility of attack on security forces in Quetta,’ a statement on their Facebook page said.

- 'Conspiracy against Muslims' –

Pakistan is one of only two countries where polio, a crippling childhood disease, remains endemic. Attempts to eradicate it have been badly hit by militant attacks on immunisation teams that have claimed nearly 80 lives since December 2012.

Islamist groups including the Taliban say the polio vaccination drive is a front for espionage or a conspiracy to sterilise Muslims. 

In 2014 the number of polio cases recorded in Pakistan soared to 306, the highest in 14 years, falling to 52 in 2015.

The most recent attack came in November last year, when unknown gunmen shot and killed the head of an immunisation programme in the Khyber Pakhtunkhwa district of Swabi.

Islamist opposition to all forms of inoculation mounted after the CIA organised a fake vaccination drive to help track down Al-Qaeda's former leader Osama Bin Laden in the Pakistani garrison town of Abbottabad.

The terror chief was killed during a US special forces raid in 2011.

Balochistan, Pakistan's largest but most impoverished province, is also home to a raging insurgency that has claimed the lives of hundreds of soldiers and militants since it re-ignited in 2004, with rebels often attacking government installations and personnel. 

The province's roughly seven million inhabitants have long complained they do not receive a fair share of its gas and mineral wealth.