Two policemen who were escorting a polio vaccination team have been shot dead in Pakistan's north-west Khyber Pakhtunkhwa province.

The policemen were attacked by unidentified gunmen in the Dera Ismail Khan district.

More than 40 people linked to the polio vaccination programme have been killed in Pakistan since 2012.

The Taliban oppose the polio programme and have been responsible for similar attacks in the past.

They say the vaccinations are a cover for foreign espionage.

Militants have also accused health workers of being part of a Western plot to sterilise Muslims.

A bomb attack on a polio vaccination team in north-west Pakistan killed at least 11 people earlier this month.

In Tuesday's violence, a roadside bomb went off as the police-guarded convoy drove through a village near the Afghan border.

The blasts were reportedly followed by a fierce gun battle between security forces and the militants.

Pakistan is one of only three countries where polio remains endemic, along with Nigeria and Afghanistan.

According to the World Health Organisation, Pakistan recorded 91 cases of polio last year, up from 58 in 2012.

巴基斯坦警方12日称，巴基斯坦卡拉奇市发生帮派火并事件，包括4名女性在内的12人死亡，39人受伤，伤者中有15名小学生。

巴基斯坦高级警官巴希尔称，此次冲突发生在当地时间12日早，两个帮派使用重型武器交火，并用火箭筒和手榴弹互相攻击。

巴希尔表示，帮派冲突的起因是其中一个帮派前一天晚上绑架了另一个帮派的一位成员。

报道称，冲突仍未结束，现场可以听到枪声，警方在阻止记者进入该区域。