At least 12 people were killed Friday in a fresh clash between two tribal groups over the distribution of irrigation water in Pakistan's northwestern Kurram region, a media report said.

The clash occurred between the Shalozan and Shalozan Tangi tribes in upper Kurram, DawnNews reported quoting officials and residents.

Heavy arms were used in Friday's fighting in which several people were also injured.

So far, 27 people have been killed and 40 injured in clashes between the two groups over the past one week.