Remote-control robots at the quake-damaged Fukushima nuclear plant in Japan have measured a "harsh environment" for humans to work in, officials said.

The measurements, which will complicate efforts to stabilize the damaged reactors, came a day after the company operating the Fukushima Daiichi plant said it would take until the end of the year to bring the crisis under control, the BBC reported Monday.

Robots measured elevated levels of radiation inside the buildings housing reactors Nos. 1 and 3 Sunday.

Plant operator Tokyo Electric Power Co. said exposure to the radiation levels measured in the No. 3 reactor for 4 1/2 hours would exceed the emergency safety limit for power plant workers.

"It's a harsh environment for humans to work inside," said Hidehiko Nishiyama of Japan's Nuclear and Industrial Safety Agency.

Operator TEPCO said it hoped to decrease radiation leaks in three months and to cool the reactors within nine months.