The Government has lost a High Court battle against environmental campaigners over pollution levels and will now need to draw up new, more ambitious plans to reduce emissions.

Environmental lawyers ClientEarth took legal action following what it called “continuing failure to tackle the national air pollution crisis”.

Presiding over the case, Mr Justice Garnham said the Government had failed to take steps to bring the UK into compliance with European pollution laws “as soon as possible”.

Ministers will now need to put in place new plans to reduce nitrogen dioxide pollution.

The Government could appeal the decision, but if it fails, it will need to come up with more ambitious plans to tackle emissions.

ClientEarth previously won a case against the Government at the Supreme Court in April 2015.

“I am pleased that the judge agrees with us that the Government could and should be doing more to deal with air pollution and protecting people’s health. That’s why we went to court,” said James Thornton, ClientEarth’s chief executive. “The time for legal action is over. This is an urgent public health crisis of which the prime minister must take personal control.”

“I challenge Theresa May to take immediate action now to deal with illegal levels of pollution and prevent tens of thousands of additional early deaths in the UK. The High Court has ruled that more urgent action must be taken,” he added.. Britain is watching and waiting, prime minister,” he added.

Responding to the ruling, a statement from the Department for Environment, Food and Rural Affairs said the Government accepts the decision and it will “carefully consider this ruling, and our next steps, in detail”.

“Improving air quality is a priority for this Government and we are determined to cut harmful emissions,” the statement added. “Our plans have always followed the best available evidence –¬†we have always been clear that we are ready to update them if necessary and have been at the forefront of action in Europe to secure more accurate, real-world emissions testing for diesel cars.”