Thousands of acres of parkland in London and landmarks including Trafalgar Square and Parliament Square should become smoke-free zones, a report has said.

The recommendations could become a blueprint for the rest of Britain, according to report author and cancer specialist Lord Darzi, who was appointed by Mayor Boris Johnson to chair the London Health Commission.

More than a million Londoners smoke, and 67 of the city's schoolchildren - equivalent to two classrooms full - take up the habit every day, the report said, concluding that the capital faces a public health emergency.

The plans, if implemented, could be an example to other areas of the UK, Lord Darzi said.

He said: "The ideas and proposals in this report have been developed for London.

“Yet they could just as easily apply to other big cities in the UK - London should be a leader, not an exception.”

The guidelines have been endorsed by Michael Bloomberg, the former mayor of New York, where all of the city's parks and beaches are smoke-free areas.

He said it would be a "major achievement" for London which has more than 20,000 acres of parkland, covering 40 per cent of the city.

The proposals have also been praised by Chief Medical Officer for England, Professor Sally Davies.

She said: "We all know smoking is bad for health.

“So I welcome any measures to reduce both active smoking and its role modelling in front of children."

Lord Darzi said 8,400 people in London die each year from the effects of tobacco, and warned that despite regulations on advertising cigarettes, children are being influenced by the adults they see smoking.

He said: "As a cancer surgeon working in the NHS, I see the terrible consequences for smokers and their families. We must do more to help people quit and discourage kids from taking it up."

Lord Darzi, who suggests a London health commissioner should be appointed to manage the new recommendations, said the measures are a way to help people make healthier decisions in life.

Anti-smoking campaign group ASH welcomed the report but Simon Clarke of pro-smoking group Forest said a ban would be "outrageous".

In a blog post he wrote: "A ban on smoking in parks and squares would be outrageous.

“There's no health risk to anyone other than the smoker. If you don't like the smell, walk away.

"Tobacco is a legal product.

If the chief medical officer doesn't like people smoking in front of children she should lobby the Government to introduce designated smoking rooms in pubs and clubs so adults can smoke inside in comfort.

"The next thing you know we'll be banned from smoking in our own gardens in case a whiff of smoke travels over the fence."

The report, due to be launched by Lord Darzi and Mr Johnson, has further recommendations to improve health, including minimum pricing for alcohol, traffic-light labelling on restaurant menus, restrictions on "junk food outlets" near schools, Oyster card discounts for people who walk part of the way to work and measures to reduce air pollution.

It also calls for a £1bn investment to modernise GP surgeries, one third of which the report found to be "very poor" or "unacceptable".

Other measures in the Better Health for London report include selling off unused NHS land and giving new mothers control of some of the payment for their care.