At least 32 people were killed and 47 wounded in sectarian clashes in northwest Pakistan, an official said on Saturday, two days after attacks on Shi'ite passenger convoys killed 43.

Sporadic fighting between Sunni and Shi'ite Muslims in the mountainous Khyber Pakhtunkhwa province bordering Afghanistan has killed around 150 over the past months.

"Fighting between Shi'ite and Sunni communities continues at multiple locations. According to the latest reports, 32 people have been killed which include 14 Sunnis and 18 Shi'ites," a senior administrative official said on condition of anonymity on Saturday.

On Thursday, gunmen opened fire on two separate convoys of Shi'ite Muslims travelling with a police escort in Kurram, killing 43 while 11 wounded are still in "critical condition", officials said.

In retaliation, Shi'ite Muslims on Friday evening attacked several Sunni locations in the Kurram district, once a semi-autonomous region, where sectarian violence has resulted in the deaths of hundreds over the years.

"Around 7 pm (1400 GMT), a group of enraged Shi'ite individuals attacked the Sunni-dominated Bagan Bazaar," said a senior police officer stationed in Kurram.

"After firing, they set the entire market ablaze and entered nearby homes, pouring petrol and setting them on fire. Initial reports suggest over 300 shops and more than 100 houses have been burned," he said.

Local Sunnis "also fired back at the attackers," he added.

Javedullah Mehsud, a senior official in Kurram said there were "efforts to restore peace ... (through) the deployment of security forces" and with the help of "local elders." (AFP)