Media playback is unsupported on your device Media caption Shadow health minister Luciana Berger: "It would make a world of difference to hundreds of thousands of children"

MPs have backed calls for a ban on smoking in cars in England and Wales when children are passengers.

They voted in favour of a Labour-supported amendment to the Children and Families Bill by a majority of 269.

This will give Health Secretary Jeremy Hunt the power to bring in a ban in England, while Welsh Government ministers will decided in Wales.

Last week, more than 700 experts wrote to MPs urging them to back change. But critics say legislation is not needed.

The amendment - passed by 376 votes to 107 - empowers, but does not compel, ministers to make it a criminal offence for drivers to fail to prevent smoking in their privately owned vehicles when children are present.

'Great victory'

The UK government gave its MPs a free vote on the issue and Prime Minister David Cameron missed the vote because he is staying in the South West overnight to visit areas affected by flooding.

Analysis Much of the debate about banning smoking in cars has been talked about in terms of protecting children. That is understandable. Research published in 2009 showed that a single cigarette in a stationary car could produce levels of second-hand smoke 11 times greater than that found in a smoky bar. Although it should be pointed out that the study also said if the car was moving and a window open it reduced the toxins to well below that level. But it is also an inescapable fact that this issue is the latest in the fight to make smoking socially unacceptable. From the smoking ban to the warnings on cigarettes, one of the underlying aims of all interventions is that they should push smoking away from what is considered normal behaviour. It is now up to ministers to decide whether they want to take this next step. At the moment, they are saying there are no immediate plans, but that could easily change.

For Labour, shadow health minister Luciana Berger said: "This is a great victory for child health which will benefit hundreds of thousands of young people across our country. It is a matter of child protection, not adult choice."

She added: "The will of Parliament has been clearly expressed today and this must be respected. Ministers now have a duty to bring forward regulations so that we can make this measure a reality and put protections for children in place as soon as possible."

A Department of Health spokesman said: "Second-hand smoke is harmful to children and it is right that this has been debated in Parliament. We will now determine how this amendment should be taken forward."

In the meantime, Public Health England would continue its campaign to "ensure parents fully understand the dangers of second-hand smoke and are encouraged to stop smoking in the home or car if there is a child present", he added, saying: "Evaluation of those campaigns shows they are increasing awareness of the risks of second-hand smoke as well changing attitudes and behaviours."

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 House of Lords passed the amendment to the Children and Families Bill last month. The bill returned to the Commons on Monday for debate.

Labour has said that if the measure does not become law before the next election, it will be included in its manifesto.

Opening the debate in the Commons, Health Minister Jane Ellison said the government would "listen to what Parliament has to say on the important principle that it should legislate" to ban smoking in cars containing children.

Media playback is unsupported on your device Media caption Pat Nurse, smoker: "The government has no right to tell me what to do"

But there were "many different ways of acting in this area", she added.

Following the Commons vote, a Welsh Government spokesperson said: "We have consistently stated that we will consider the possibility of legislation once we have fully evaluated the impact of the campaign. We have commissioned studies of children's exposure to second-hand smoke in cars and results will be available later this year."

In a letter published in the British Medical Journal last week, respiratory health experts argued that exposure to second-hand smoke was a "major cause of ill-health in children", particularly among the most disadvantaged groups.

It said smoking in cars exposed children to particularly "high amounts of tobacco smoke" and there was now a consensus that children should be protected from such unnecessary hazards.

Smoking in cars Smoke can stay in the air for up to two and a half hours even with a window open.

Second-hand smoke contains more than 4,000 chemicals, some of which are known to cause cancer.

Exposure has been strongly linked to chest infections, asthma, ear problems and cot death in children.

Research indicates that 300,000 children in the UK visit a GP each year because of the effects of second-hand smoke, with 9,500 going to hospital.

Smoking in a car creates a higher concentration of toxins than in a bar. Some research has put it at 11 times higher.

Bans on smoking in cars when children are present already exist in some US states, including California, as well as in parts of Canada and Australia.

It also said there were precedents for a ban, including laws to require people to wear seatbelts and, more recently, the ban on using mobile phones while driving.

Bans on smoking in cars carrying children already exist in countries including Australia, Canada, South Africa and the US.

Simon Clark, director of smokers' lobby group Forest, said smoking in cars with children was "inconsiderate", but there was "a line the state shouldn't cross when it comes to dictating how people behave in private places".

In Scotland, Liberal Democrat MSP Jim Hume has indicated he will be presenting a bill this year to bring in a ban, while Northern Ireland's health minister has announced plans for a consultation on the issue.