TOKYO (AFP) - Tokyo Electric Power Co. (TEPCO) said Monday it had monitored record high radiation at the Fukushima Daiichi nuclear power plant crippled by the March 11 tsunami. TEPCO said radiation levels reached at least 10 sieverts per hour near the debris left between the number one and number two reactors of the plant at the centre of the ongoing nuclear crisis. The previous record was three to four sieverts per hour monitored inside the number one reactor on June 3. "Three plant workers were exposed to a dosage of four millisieverts while they were monitoring radiation," a TEPCO spokeswoman said. "We are still checking the cause of such high levels of radioactivity."