Experts have postponed a decision on whether a fault line underneath Japan's only operating nuclear plant is active and the facility should be closed.

A five-member team commissioned by the Nuclear Regulation Agency inspected the Ohi plant in western Japan last week to check a suspected fault line. Two of Ohi's four reactors resumed operation in July for the first time since a nuclear crisis last year at a separate plant hit by a quake and tsunami.

The experts agreed Sunday that part of Ohi's underground structure slid as far back as 125,000 years ago but they couldn't tell if it was because of an active fault line. They will meet again this week.

Chief regulator Shunichi Tanaka has suggested a plant closure if the fault line is judged active.