The operator of the crippled nuclear power plant leaking radiation in northern Japan announced a plan Sunday to bring the crisis under control within six to nine months and allow some evacuated residents to return to their homes.

But officials stressed the roadmap for ending the crisis at the Fukushima Dai-ichi nuclear power plant was only a first step, that conditions remain unstable, and that it remains unclear when the government will let evacuees go back.

Prime Minister Naoto Kan, facing pressure both at home and abroad to resolve Japan's worst-ever nuclear power accident, directed Tokyo Electric Power Co. to draw up the plan.

"Given the conditions now, this is best that it could do," said Hidehiko Nishiyama of the government's Nuclear and Industrial Safety Agency. "But it cannot be said that the reactor has stabilized."

The roadmap, presented by TEPCO Chairman Tsunehisa Katsumata at a news conference, includes plans to cover the damaged reactor buildings to contain radiation and eventually remove the nuclear fuel.

"We sincerely apologize for causing troubles," Katsumata said. "We are doing our utmost to prevent the crisis from further worsening."

The company is focusing first on cooling the reactors and spent fuel pools and reducing the level of leaking radiation, decontaminating water that has become radioactive, reducing the amount of radiation released into the atmosphere and soil, and lowering radiation levels in the evacuation area, he said.

In the next stage, it aims to firmly control the release of radioactive materials, achieve a cold shutdown of the reactors and temporarily cover the reactor buildings, Katsumata said.