The wider growing and selling of genetically modified crops has received its strongest government backing to date from the new environment secretary, Caroline Spelman.

At present no GM crops are commercially grown in the UK, and the previous Labour government was nervous of promoting GM foods because of fear of a renewed public backlash against "Frankenstein foods". But in her first interview in charge of the department of environment food and rural affairs, the minister committed the new coalition to becoming the most pro-GM government yet, saying she was in favour of GM foods "in the right circumstances".

"GM can bring benefits in food to the marketplace. The sale should not be promoted by the taxpayer. [New Environment minister] Lord Henley has approved a trial of a potato blight-resistant variety. That's the kind of modification that can reduce the amount of agro-chemicals which need to be applied," said Spelman, who spent 15 years in the agriculture industry and worked as director of a biotechnology lobbying firm.

She added: "There are benefits to developing countries, like drought resistance or resistance to high salt content in water. The principle of GM technology is [OK] if used well. The technology can be beneficial."

But in a reference to Labour's £500,000 plan to gauge public attitudes to the controversial technology, she said she was not in favour of using taxpayers' money to promote the industry. Two members of the Food Standards Agency committee in charge of the plan recently resigned in protest.

"The Food Standards Agency should not be spending taxpayers' money promoting GM foods," Spelman said.

Visiting the Guardian's head office in London before the UN's world environment day tomorrow, Spelman, 52, also said she would be "implacable" in defence of green belt land and would allow new protected areas to be created to halt the continuing loss of nature, would back badger-culling but would not prioritise the promised vote on the repeal of the hunting with hounds act.

A Conservative MP for a "green belt constituency" on the edge of Birmingham, said she would stop the practice of building on existing green belt sites in return for creating new green belt land in areas with little or no development threat, and would abolish regional planning committees allowing local authorities to take responsibility for protecting their own communities from urban sprawl.

However national "strategic" projects would still go ahead on green belt, including proposed new high-speed rail lines, she said.

"I'm implacable on green belt," added the Meriden MP. "Green belt was created in the 1950s in order to protect the countryside from urban sprawl ... and green belt needs to be maintained."

Although the Conservative-Liberal Democrat coalition agreement did not propose a national scheme for increasing protected areas, Spelman said local planning authorities would be encouraged to protect green space – with the likely result that protection would increase.

"Every local authority will negotiate with the community where housing is built, where green space is protected, and where new green space is created," she said.

In advance of a major meeting of the International Whaling Commission later this month (JUNE), Spelman said the UK government would not support the IWC's proposed "peace plan", which would lift the ban on limited commercial whale hunting in return for banning "scientific" whaling. Scientific whaling is currently allowed and many suspect is used as a cover by Japan and other countries for killing whales for their meat.

Instead, Spelman said she was trying to get agreement in the European Union, whose countries make up 25 of the 88 members of the IWC, for an alternative compromise, which would still outlaw commercial whaling, but allow indigenous communities in countries such as Denmark to carry out limited "subsistence" hunting. The British proposal would continue to allow whales to be killed for scientific research, though it "mustn't be a proxy for hunting whales commercially", said Spelman.

Spelman also confirmed that badgers, which are protected in law but have been at the centre of a passionate debate about the spread of bovine tuberculosis, would be culled in England. The decision will please livestock farmers but is expected to enrage many conservationists.

"It [the policy] has to be led by science," she said. "We will take a science-led package of measures including culling and vaccination."

Spelman confirmed that – as the coalition agreement and Conservative manifesto promised – there would be a free vote in this five-year parliament on repealing Labour's hunting act, which banned hunting foxes with hounds, but warned it was "not a priority".

"The absolute priority at the moment is to get to grips with the economic crisis; the fact is recognised by the [pro-hunting lobby group] Country Alliance," she said. Asked how the vote was likely to go, Spelman added: "I can't possibly answer that question because it's a free vote."