TOKYO — A new leak of toxic radioactive water, the third in a week, may have sprung from one of the seven underground storage tanks at Tokyo Electric Power Co.’s Fukushima plant, the site of a 2011 earthquake and tsunami, which led to the meltdown of three nuclear reactors.

The leak was discovered as Tepco, as the company is known, transferred radioactive water to the No. 1 underground pool from the No. 2 tank where a separate escape of water was found last week, Masayuki Ono, a senior official at Tepco’s nuclear power and plant siting division, told reporters in Tokyo Tuesday.

The transfer of contaminated water to the No. 1 tank has been suspended, he said.

“We cannot stop using all the underground tanks right away because we don’t have enough ground storage space,” he said. Tepco is trying to find space where the remaining water from the leaking underground pools can be stored, Ono said.

The leaks have been found in the pools where Tepco stores some of the nearly 280,000 tons of highly radioactive water used to cool the crippled reactors at the Fukushima Dai-Ichi plant.

The latest leak highlights missteps in Tepco’s management of radioactive water after the March 2011 quake and tsunami led to three reactors melting down and the escape of radiation, causing the evacuation of about 160,000 people.

Tepco is still investigating the cause of leaks and doesn’t know how much water may have gotten out of the No. 1 tank, Ono said.

Tepco Monday said about 167 tons of radioactive water may escape the No. 2 underground tank while as much as 3 liters of contaminated water may have leaked from the No. 3 tank.

Water Transfers

The company had planned to complete transferring the remaining water stored in the No. 2 tank to other underground pools by tomorrow, Japan’s nuclear regulator said earlier Tuesday in an emailed statement.

About 280,000 tons of highly radioactive water is stored in tanks at the Dai-Ichi plant, according to Tepco’s latest data. That’s enough to fill about 112 Olympic-sized swimming pools, according to Bloomberg News calculations.

Tepco plans to accelerate plans to install new tanks that can store 126,000 tons of water as much as possible, Tepco spokesman Masateru Araki said. The utility originally planned to complete the construction of the additional tanks by the end of September, he said.