An enormous row broke out on Wednesday after the chief nuclear safety inspector gave Britain's reactor fleet the all-clear and made modest "recommendations" to be incorporated in the planned new plant design.

Critics immediately accused Mike Weightman of rushing to judgment and "complacency" in his interim report on the lessons to be learned from the Fukushima atomic crisis.

The safety boss said there was no need to curtail the operations of atomic plants in Britain, given that conditions in Japan were so different, but wanted a review of backup power supplies, ventilation procedures and plant layout.

"We are not complacent. No matter what the differences are, and how high the standard of design and subsequent operation of the nuclear facilities here in the UK, the quest for improvement must never stop," Weightman argued.

The chief nuclear inspector denied he was under political pressure to keep the atomic bandwagon rolling in Britain, and said energy companies would need to take on board his list of 26 recommendations.

"We are independent and do not operate under government auspices... We need to be open to the UK public," he argued. "We are not just asking them [plant operators] to do things. We put the onus on the industry... Make no mistake: while I will seek reassurances from the industry, if I am not satisfied, they will not operate," he added.

The interim report – to be followed by a fuller report in September, following Weightman's own visit to Japan, was demanded by the energy secretary, Chris Huhne, in the aftermath of the 9-magnitude earthquake and tsunami that battered the Japanese coast and caused an explosion at a nuclear plant, leading to radioactive releases.

Weightman's report was welcomed by Huhne, EDF, the French company at the forefront of plans to build new reactors, and the nuclear workers' union, Unite, but came under attack from Greenpeace and other nuclear sceptics.

Doug Parr, policy director at Greenpeace, said the regulator's review of safety essentially concluded that the industry should go away and think about it. "Many people will regard that as complacent, given the huge cost and misery inflicted by the Japanese accident, and this cannot inspire confidence in Britain's nuclear regulators. Even as the struggle to control Fukushima reactors continues, it appears Huhne has rushed to judgement on the safety of reactors to keep the timetable for new nuclear power on track," he added.

Paul Dorfman, an academic and member of the Nuclear Consultation Group, said it was an "outrage" that conclusions on Fukushima had been made while facts from Japan remained so sketchy and the crisis was far from over. He added: "There is really not enough information around yet to base any rational decisions on."

But Weightman, insisting he could still amend the recommendations in his final report, concluded that it was "not credible" to expect a Japanese-style earthquake in the UK, and he pointed out that existing and planned nuclear power stations in this country were of a different design from those at Fukushima.

Flooding risks were unlikely to prevent the construction of new nuclear power stations at potential development sites in the UK, all of which were on the coast, he added.

The government is reviewing plans by EDF and others to develop a new suite of nuclear reactors on existing British sites to maintain electricity supplies and cut greenhouse gas emissions as power stations of an older generation are shut down.

Huhne made it clear that the report paved the way for new reactors. "I am pleased that today's report confirms that the UK's current safety arrangements are working. We want to see new nuclear as part of a low-carbon energy mix going forward, provided there is no public subsidy. The chief nuclear inspector's interim report reassures me that it can," he added.

Unite, which represents 40,000 workers in energy and utilities, said the positive interim report from the UK's chief nuclear inspector was the green light for fast-tracking newbuild.

"The government must now publish its national energy policy statements without delay and get on with the job of creating the right environment for creating a low-carbon energy infrastructure fit for the 21st century," said Kevin Coyne, Unite's national officer for energy. "This includes commissioning the first newbuild nuclear power station for a generation at Hinkley Point."

On Tuesday, Germany's environment minister, Norbert Röttgen, said the results of post-Fukushima safety checks on its nuclear reactors showed there was no need to switch plants off now. Röttgen said there was "no argument to say that we must get out of [nuclear power] in a hurry, overnight for safety reasons." But he added that Germany was committed to phasing out nuclear, as announced by chancellor Angela Merkel in March: "It remains the case that we should find a way to give up nuclear energy as soon as is sensible," he said. The end was approaching for Germany's seven oldest nuclear plants, because they would not be able to withstand a large plane crash he said.

Japan's prime minister, Naoto Kan, said last week that the country was starting from scratch on its energy policy and was likely to abandon plans to increase the amount of Japan's electricity provided by nuclear from the existing 30% to 50%.