A system to treat contaminated water that is impeding repairs at Japan's damaged nuclear power plant is not performing as well as hoped but should be functioning fully next month, a government official said Thursday, June 23, AP reported.

Since the March 11 tsunami, workers have cooled the reactors and spent fuel by pumping fresh water, which becomes contaminated with radiation. About 110,000 tons of tainted water have accumulated, threatening to leak into the sea and posing health risks and logistical hurdles to the workers struggling to make repairs at the plant.

"The contaminated water problem is the biggest barrier right now," said Goshi Hosono, director of the government's nuclear crisis task force. "We are anxious to stabilize the treatment system one way or the other."

Problems were expected along the way, he said, but added that he wanted to get the system fully operational by the end of June and running stably by mid-July.

"The water treatment system is a key step toward bringing the reactors to cold shutdowns," he said.