At least 34 people were killed and more than 100 injured in clashes between rival Sunni and Shia muslim groups in north-west Pakistan, officials said Saturday.

The running battles broke out after Friday prayers in Parachinar, a tribal region near the Afghan border, when gunmen opened fire on a Sunni mosque injuring two people, the local administrator Dr Fakhar Alim told Deutsche Presse-Agentur dpa in a telephone interview.

The heavily armed groups were using rocket launchers and mortar fire in the ongoing firefight, prompting the authorities to impose an indefinite curfew in the town.

Military troops are also being deployed to the region, Alim said.

At least 34 bodies had been brought to the hospital so far, local hospital officials said while unconfirmed reports put the death toll at over 45.

"We have given treatment to more than 100 people since yesterday. Two dozens of them are still in critical condition," said a medical officer, Habibur Rehaman.

Tensions between rival sectarian groups have been running high for several months in Parachinar. In April, more than 60 people were killed in armed clashes between the sides.

The riots led to a curfew lasting several weeks which was only lifted after the rival factions had agreed to a peace deal.