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TOKYO, July 18 (Reuters) - Tokyo Electric Power Co. <9501.T> has asked six utilities for supplies of electricity to help fill an anticipated shortage from the shutdown of its quake-hit nuclear facility, company officials said on Wednesday.

The plant, the world's largest, remains closed after a strong tremor on Monday caused radiation leaks among other problems.

It is unclear when TEPCO will be able to resume operations, raising concerns about a supply crunch ahead of the peak summer season in the capital Tokyo and surrounding areas the company services.

TEPCO has asked the six companies to supply power from about late July to the end of September, although it has not specified how much it requires.

"We would like to ask for as much electricity as possible from each utility," Kaoru Yoshida, TEPCO's corporate communications manager told reporters.

TEPCO added it would consider asking other utilities for help.

The six companies it has already asked are: Tohoku Electric Power Co. <9506.T>, Kyushu Electric Power Co. <9508.T>, Chugoku Electric Power Co.<9504.T>, Shikoku Electric Power Co. <9507.T>, Chubu Electric Power Co. <9502.T> and Kansai Electric Power Co. <9503.T>.

As of Wednesday, TEPCO has reported 53 problems at its 8,212 megawatt-power Kashiwazaki-Kariwa nuclear plant in northwestern Japan following the 6.8 magnitude tremor.

There are seven nuclear reactors at the plant. The No. 1 unit started operations in September 1985 and the newest No. 7 unit entered commercial operations in July 1997.

Public concern was likely to increase after TEPCO on Wednesday revised up the level of radiation in water that leaked.

The leaks into the ocean and atmosphere from the plant in the city of Kashiwazaki, near the epicentre of the quake that killed nine people, have renewed fears about the safety of Japan's nuclear industry.

The government told Asia's largest utility on Tuesday that it must delay the restart of the plant until its safety has been confirmed.

The city where the plant is located also said the facility should stay closed until safety was assured.

Safety concerns were also raised by the international nuclear watchdog.

"It's clear that this earthquake, as TEPCO, the operating company, indicated, was stronger than what the reactor was designed for," International Atomic Energy Agency head Mohamed ElBaradei told reporters in Kuala Lumpur on Wednesday.

ElBaradei urged a thorough probe to find out what went wrong.

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