CAMPAIGNERS have welcomed plans backed by MPs which could save hundreds of thousands of children from being exposed to second-hand smoke in cars.

Leading medical charities said they were "delighted" that Parliament voted in favour of paving the way for legislation which could outlaw smoking in vehicles carrying children.

The Commons gave the Health Secretary the power to impose a ban despite the opposition of some MPs, including leading members of the Cabinet.

Ministers were granted a free vote on the measure - successfully introduced by Labour in a House of Lords amendment to the Children and Families Bill - meaning they were not tied to a party line.

The British Medical Association (BMA), which has campaigned for a ban since 2011, said the vote was an "important step forward in reducing tobacco harm".

Dr Penny Woods, chief executive of the British Lung Foundation, said: "Having campaigned on this issue for many years, we're absolutely delighted that MPs have backed the ban on smoking in cars carrying children.

"This could prove a great leap forward for the health of our nation's children.

The charity estimates that in England more than 430,000 children aged 11 to 15 are exposed to second-hand smoke in cars every week.

Research published by the organisation last year concluded that 185,000 children of the same age are exposed to smoke while in the family car on "most days", if not every day.

Deborah Arnott, chief executive of health charity Ash (Action on Smoking and Health) described the vote as "an historic victory for Parliament and for children's health".

Tory and Liberal Democrat MPs joined forces with Labour MPs to approve the ban by 376 votes to 107, majority 269.

Prime Minister David Cameron missed the vote while visiting flood-stricken areas in the south west.

Pro-smoking groups branded the move as an "unnecessary intrusion".

Simon Clark, director of the smokers' group Forest, said he was "disappointed but not surprised" by the decision and accused the Government of being "spineless".

He added: "Legislation will have very little impact because so few adults still smoke in cars carrying children. Those that do will carry on because it will be very difficult to enforce.

"Government has banned smoking in public places. Now they're going to ban it in a private place. The home will be next."