Ministers are funding graphic adverts showing a tumour growing on a cigarette in an attempt to tackle smokers' ignorance about how lighting up can damage their body.

The Department of Health is spending £2.7m on a nine-week campaign of graphic advertisements warning smokers that as few as 15 cigarettes can cause a cancerous tumour.

The TV and billboard ads, which show a tumour developing on a cigarette as a man smokes it, are being introduced after research showed that more than one in three smokers believe health risks associated with their habit have been overplayed.

"It is extremely worrying that many people still underestimate the serious health harms associated with smoking. We want smokers to understand that each packet of cigarettes increases their risk of cancer," said Professor Dame Sally Davies, the government's chief medical officer for England.

They are the first hard-hitting anti-smoking ads since the arresting "fatty cigarette" campaign in early 2004, which depicted deposits being squeezed from a smoker's artery. It was credited with prompting many smokers to try to give up.

The latest tumour ads are targeted particularly at young people who may not have not seen such graphic warnings since then. The campaign is being accompanied by a renewed effort by NHS stop-smoking services to help those who want to quit.

The move represents a U-turn by the coalition, which said it would not fund public health advertising campaigns when it took power. But evidence showing that such tactics are effective, and an apparent recent fall from 40% to 35% in the number of smokers who try to quit in any one year, have convinced ministers to approve the campaign.

MPs and peers in the all-party parliamentary group of smoking and health at Westminster voiced concern about the DH no longer funding hard-hitting tactics and had urged ministers to think again "as a matter of urgency".

The British Medical Association, which represents doctors, backed the move. "Hopefully it will help smokers to make the decision that 2013 will be the year the they quit smoking. Smoking is the single largest cause of preventable illness and premature death in the UK. Doctors see at first hand the damage it causes to individuals as well as those around them," said a spokeswoman said.

Martin Dockrell, head of policy at Action on Smoking and Health, said: "Most smokers say they want to quit and tend to be prompted to act by public service ad campaigns and as New Year resolutions. The problem is that smokers tend to under estimate their risk and also think of the risks and benefits as being far in the future. This campaign has been designed to show smokers graphically how every extra cigarette adds to the risk of cancer.

"A few months ago, we saw the first Stoptober campaign, a fun challenge for people to do together. This is a very different campaign responding to the clear evidence that hard hitting campaigns trigger smokers to quit."

• For more information on how to quit smoking visit NHS Choices website.