President Donald Trump’s ban on issuing new wind energy permits has been ruled “unlawful” by a US court.

In January the president signed an executive order freezing federal approval of offshore and onshore wind projects, halting construction of several projects in the US that were already under way.

Some 17 states and a New York-based clean energy group sued the government, sparked by a stop work order imposed on the Empire Wind 1 project, a vast wind farm planned off the coast of New York aimed at powering 500,000 homes.

On Monday, Massachusetts district court judge Patti B Saris vacated Trump’s order, saying it was “arbitrary and capricious and contrary to law”.

In her judgement, Judge Saris said federal agencies had failed to “provide a reasoned explanation for the change” and justification for the new policy.

New York Attorney General Letitia James described the court’s ruling as “a big victory in our fight to keep tackling the climate crisis” in a social media post.

“We won our lawsuit and stopped the Trump administration from blocking an array of new wind energy projects,” she said.

The states, led by New York, sued in May, after the Interior Department ordered Norway’s Equinor to halt construction on its Empire Wind project

While the Trump administration has since allowed work on Empire Wind to resume, the states have argued the wider freeze on permits for other projects is hitting the US economy.

Trump has sought to boost government support for fossil fuels after campaigning for the presidency under the slogan “drill, baby, drill.”

Days after his return to office, Trump said “we’re not going to do the wind thing” and called them “big, ugly windmills” that were dangerous to wildlife.

Trump has previously claimed, without evidence, that wind turbines kill whales.

According to its website, the Empire Wind project is expected to take two years to complete and be fully operational by the end of 2027.

Before becoming president, Trump battled – and ultimately failed – to stop the construction of a wind farm off the coast of his golf course in Aberdeenshire, Scotland.