Tokyo Electric Power Company (TEPCO) Tuesday asked for an extra $8.5 billion in aid from a government-backed fund to help it compensate families affected by the Fukushima nuclear crisis.

The request, if granted, would bring the total amount of aid the utility has sought from the Nuclear Damage Compensation Facilitation Corporation up to 1.7 trillion yen ($21 billion) from a previous 1.01 trillion yen.

TEPCO said the increase results from government moves to widen eligibility criteria for claimants and to alter the evacuation zone restrictions around the stricken plant, which was hit by the huge waves of March 11.

The decisions have increased both the amount of compensation the firm is liable for and the number of people entitled to claim, it said.

"We submitted a change to the amount of financial assistance" required, TEPCO said in a statement.

Japan's industry minister will review the request.