Radioactivity levels in one part of the stricken Fukushima Daiichi nuclear plant are 10m times higher than normal, Japanese officials have said, amid warnings that the operation to avert disaster at the facility could last for months. Tests on the surface of a pool of water that has formed in the No 2 reactor revealed radioactivity of 1,000 millisieverts (mSv) per hour four times the level deemed safe by the government. The worker carrying out the test reportedly fled before taking a second reading. Hidehiko Nishiyama, a spokesman for Japan's nuclear and industrial safety agency [Nisa], said, "This is quite a high figure," adding that the water "is likely to be coming from the reactor". The discovery prompted another evacuation of workers at the site, halting work to pump and store radioactive water that has built up in the turbine buildings of three of the plant's six reactors.