TOKYO - Japan will allow extensions of up to 20 years to a planned 40-year limit on the life of nuclear reactors, in line with US standards, the government said.

Japan is set to introduce the limit in the wake of last year's Fukushima nuclear crisis, the world's worst since Chernobyl 25 years ago.

The government will allow nuclear plant operators to file for an extension for each reactor only once and permission would only be granted if certain conditions were cleared.

Under the current system, nuclear plant operators can file for an extension of operations after 30 years and are usually granted 10-year extensions with no limit on how often they reapply for those extensions as long as they provide required maintenance.

The ruling party plans to submit the bills on limiting the length of reactor operations in the current session of parliament starting later this month.