The Madagi and Mali Khel tribes have been fighting since Wednesday, when a gunman opened fire at a council negotiating a decades-long dispute over farmland, local police official Murtaza Hussain said.

While no one was wounded in that attack, Hussain said it reignited longstanding religious tensions between the clans who live side-by-side in the district of Kurram on the border with Afghanistan.

"Initially a land dispute, the issue has now escalated into sectarian violence," Hussain told AFP, confirming the conflict "claimed 35 lives" so far.

"The government and local leaders are attempting to halt the fighting through jirgas (tribal councils), but have not yet succeeded," he said, the Business Standard reported.

However, they can be particularly protracted and violent in the mountainous northwestern region of Khyber Pakhtunkhwa, where communities abide by traditional tribal honor codes.

A senior government official from Kurram district, who asked to remain anonymous, also gave a death toll of 35 but said 151 more people had been wounded.

"The conflict, now in its fifth day, has escalated into a religous dispute," he said. "All attempts to resolve the conflict have failed."