The tribes exchanged gun, rocket and mortar fire after the dispute erupted several days ago over the holy site in the restive Orakzai tribal district, a senior security official told AFP.

"We have a large presence of security personnel over there and we are trying to restore order," the official said on condition of anonymity.

Officials said the trouble broke out when clerics from the rival sects both tried to occupy the shrine, with each side claiming it belonged to them.

Clashes also have erupted in the neighbouring districts of Khurram and Hangu, an official at the Federally Administered Tribal Areas secretariat said, without giving details.

Pakistan's 80 percent majority Sunnis and minority Shias generally live together peacefully but outbreaks of sectarian violence and bombings have claimed thousands of lives in the past two decades.

More than 30 people were killed in a suicide bombing and subsequent fighting in February in Hangu.

Pakistan's tribal areas are awash with weapons left over from the anti-Soviet "jihad" in Afghanistan during the 1980s.