Tens of thousands of people are fleeing their homes in western Kenya following an army operation targeting members of a group linked to clashes over land, a Red Cross official says.

Ochiemo Cheptai, who identified himself as chairman of a local chapter of the Kenya Red Cross, told the Associated Press that on Sunday the army began bombing villages in the Mount Elgon area, where members of the Sabaot Land Defence Force are believed to be hiding.

Cheptai said up to 30,000 people have fled their homes in the past 24 hours.

Red Cross officials in Nairobi and Geneva, however, said Cheptai wasn't with the organization and were challenging the 30,000 figure, saying they have not yet assessed the numbers fleeing.

Local legislator Fred Kapondi accused the army of targeting civilians instead of pursuing militants in their hideouts. He said people are fleeing "aerial bombing and harassment from the army."

But Mohamud Birik, the local district commissioner, denied the army is targeting villagers.

Army spokesman Bogita Ongeri declined to provide details, saying only that troops were in the area to assist local officials.