Workers scanning for further leaks at the Fukushima nuclear site have discovered pockets of high radiation close to some tanks holding contaminated water, signalling another possible setback in efforts to wind down the disaster-hit facility. Tuesday’s disclosure of a leak of roughly 300 tons of highly radioactive water from a temporary storage tank had triggered concerns that some of the other 350 or so non-welded tanks in the compound might also be leaking. In a statement on Thursday evening Tokyo Electric Power, the site owner, said that it had found no further leaks but had discovered two areas of high radiation near to the bottom of two tanks. Each tank was full, suggesting there had been no loss of water. But the spots were emitting a dose of between 70 and 100 millisieverts an hour, similar to the levels measured above a puddle discovered on Monday, which was later linked to the 300-ton leakage. 100 millisieverts an hour is the maximum cumulative exposure allowed for nuclear plant workers over five years. “It is difficult to say how serious this is”, said Yoshikazu Nagai, a spokesman for Tepco, confirming that it was the first time that patrols had discovered dry spots emitting high levels of radiation. “We will investigate more.” The latest disclosure may intensify fears that Tepco, majority-owned by the government but in operational control of the Fukushima site, lacks the resources and the knowhow to manage the 40-year task of decommissioning the plant crippled in the 2011 tsunami. Earlier in August Prime Minister Shinzo Abe ordered the Ministry of Economy, Trade and Industry to step up its oversight, after Tepco admitted that groundwater was mixing with contaminated water from basements and trenches before reaching the sea. On Tuesday trade minister Toshimitsu Motegi, in Brunei for a meeting to forge a free-trade pact, sent orders to Tepco to detect the source of the leak, to inspect all other tanks of the same type, and to take measures to ensure it does not happen again. But calls for a stronger hand from the state are growing louder. On Wednesday an editorial in the Mainichi newspaper said that “the government should have a sense of responsibility and play a more active role in responding to the crisis.”