Britain may back away from the use of nuclear energy because of safety fears and a potential rise in costs after the Fukushima disaster, says Chris Huhne, the energy secretary.

In an interview with the Observer, Huhne insisted that he would not "rush to judgment" until the implications of the disaster were known and a report into the safety of UK nuclear plants by the chief nuclear officer, Dr Mike Weightman, was complete. The interim findings are due in May.

"I am not ruling out nuclear now," said Huhne. But he said events in Japan could have profound long-term implications for UK policy, which is based on a three-pronged "portfolio" approach: a commitment to nuclear energy; the development of more renewable energy, such as wind and sea power; and new carbon-capture technology to mitigate the damaging environmental effects of fossil fuel-fired power plants and industrial facilities.

Huhne, a Liberal Democrat, said that Britain was in a very different position from Japan, which was vulnerable to strong earthquakes and tsunamis. The UK also used different types of reactors. But he conceded that the Japanese disaster was likely to make it more difficult for private investors to raise capital to build the eight new reactors planned by the government. "There are a lot of issues outside of the realm of nuclear safety, which we will have to assess. One is what the economics of nuclear power post-Fukushima will be, if there is an increase in the cost in capital to nuclear operators."

He said that after the Three Mile Island nuclear disaster in the US 32 years ago, it became more difficult to raise money for nuclear investment. "After Three Mile Island in 1979, nuclear operators found it very hard to finance new projects.

Huhne said he remained wedded to the "portfolio" approach, but added that nuclear energy's future, as part of the mix, had become more uncertain as leaders of other nations, including the German chancellor, Angela Merkel, openly questioned its future. "Globally, this undoubtedly casts a shadow over the renaissance of the nuclear industry. That is blindingly obvious," he said.

Any move away from nuclear – while certain to be welcomed by many Lib Dems – would alarm many in the Tory party. Tim Yeo, the Conservative chair of the environment and climate change select committee, said any such shift would be a huge mistake. "If Britain abandons or significantly delays its programme of building new nuclear power stations, there are three inevitable consequences. First, electricity prices will rise. Second, Britain will not be able to meet its carbon emission reduction targets. And third, the risk that the lights will go out will significantly increase.

"This is because other forms of low-carbon energy, such as solar or offshore wind, are more expensive than nuclear. Solar and wind are not reliable generators of electricity – on cloudy, still days they produce nothing. So they have to be backed up by reliable sources of power. If nuclear is not used, that means more gas or coal, both of which have far higher carbon emissions."

The Department of Energy and Climate Change has carried out its own projections, which show the UK could – with a massive extra commitment to renewable energy and successful use of carbon capture on a grand scale – meet its target of reducing emissions by 80% by 2050 without nuclear energy.

Huhne said: "We can do the 80% reduction in emissions by 2050 without new nuclear, but it will require a big effort on carbon capture and storage and renewables."

However, Yeo said: "Nuclear currently provides almost one-fifth of our electricity. Nearly all our existing nuclear power stations will shut by 2020. Demand for electricity will rise steadily from now on as cars, vans, etc start to use electricity and the heating of buildings relies more on electricity. It is very likely that without new nuclear power stations we will simply not build enough other forms of reliable electricity generation in time to replace the contribution nuclear currently makes."

Huhne has asked Weightman to draw up a report into the safety of UK nuclear plants, assessing their resistance to the kind of natural disasters that could hit this country, including flooding and storms. But ministers acknowledge that, even if plants are declared safe, the public perception of nuclear power has been undermined. The cost of meeting new safety conditions and insuring plants, as well as satisfying evacuation requirements in the event of a disaster, could make new reactors economically unviable.

Huhne said ministers needed to show flexibility as untried and untested technology succeeded or failed along the way. "The whole point about a portfolio is that over time – a 20-year view – some of those sources [of energy] will turn out to be much more economic and attractive than others," he said.

After the anti-nuclear Lib Dems went into coalition with the Tories last May, Huhne forged a deal under which plans for a new generation of nuclear would go ahead, but without public subsidy. He said at the time that the Lib Dems' preference for meeting the country's energy needs was still to make greater use of renewable energy, such as wind and sea power.

The deal marked a departure for Huhne from his stance in opposition. In 2007 he said: "Nuclear is a tried, tested and failed technology and the government must stop putting time, effort and subsidies into this outdated industry."