Tokyo Electric Power Corp's (TEPCO) official (C) and journalists wearing protective suits and masks stand in front of storage tanks for radioactive water in the H4 area, where radioactive water leaked from a storage tank in August, at the tsunami-crippled
Tokyo Electric Power Corp's (TEPCO) official (C) and journalists wearing protective suits and masks stand in front of storage tanks for radioactive water in the H4 area, where radioactive water leaked from a storage tank in August, at the tsunami-crippled TEPCO Fukushima Daiichi nuclear power plant in Fukushima prefecture November 7, 2013. Japan approved on October 30, 2013 a plan by TEPCO to extract thousands of nuclear fuel rods from the fuel pool of the No. 4 reactor of the Fukushima Daiichi plant. Containing radiation equivalent to 14,000 times the amount released in the atomic bomb attack on Hiroshima 68 years ago, more tha

Tokyo Electric Power Co (TEPCO), embattled operator of crippled Fukushima nuclear power plant, has detected a new radiation contaminated water leak at the plant's No. 3 reactor building.

The leak was discovered through the camera of a rubble-removing robot placed inside the No. 3 building. The images caught by the robot showed a 30-cm-wide water leak inside the facility on the first floor.

None of the water, which was flowing into the basement of the reactor building, has leaked outside the building so far, TEPCO said. According to Japan Times, the radiation level on the first floor alone of the No. 3 reactor building has reached a high 30 millisieverts per hour.

Tokyo Electric Power Corp's (TEPCO) official (C) and journalists wearing protective suits and masks stand in front of storage tanks for radioactive water in the H4 area, where radioactive water leaked from a storage tank in August, at the tsunami-crippled TEPCO Fukushima Daiichi nuclear power plant in Fukushima prefecture November 7, 2013. Japan approved on October 30, 2013 a plan by TEPCO to extract thousands of nuclear fuel rods from the fuel pool of the No. 4 reactor of the Fukushima Daiichi plant. Containing radiation equivalent to 14,000 times the amount released in the atomic bomb attack on Hiroshima 68 years ago, more than 1,300 used fuel rod assemblies packed tightly together need to be removed from a building that is vulnerable to collapse, should another large earthquake hit the area. REUTERS/Kimimasa Mayama/Pool

The Japanese utility company said it is now investigating the source of the leak.

TEPCO theorized the leaking water could be the cooling water from the reactor containment vessel. If true, it poses another problem in the plant's decommissioning process.

On Wednesday, TEPCO has received approval from the Japanese government to revive the No 6 and No 7 reactors of its Kashiwazaki-Kariwa nuclear facility.

Read: Defying Opposition, Japan OKs TEPCO Plan to Revive Closed Power Plant

The company has presented the revival plan as a visible attempt to remain afloat after the Fukushima disaster pushed it to the brink of bankruptcy.

In an interview with Bloomberg over the weekend, Naomi Hirose, TEPCO President, said the company will borrow 2 trillion yen in fresh loans from lenders and spend it on strategic investments through partnerships.

"For the sake of Fukushima's reconstruction, we have to seek growth," Mr Hirose said.

"To fulfill our responsibilities in Fukushima, we will need a lot of money and are being granted a goodly amount of the government's money," Mr Hirose added. "We have to repay it by improving corporate value."

TEPCO's net losses have reached 2.7 trillion yen for the three full fiscal years ended March 31.