Councils have been criticised for investing £20m in tobacco firms while at the same time telling people to quit the habit.

Critics have said the £19.8m invested for council workers’ pensions was in conflict with efforts to get county residents to quit.

The £1.2bn fund’s largest company investment is £11.3m in British American Tobacco with £8.5m also in Imperial Tobacco.

Oxfordshire County Council administers the fund for contributing councils. It also pays £50,000 towards the post of the county’s director of public health and just last month he said quitting smoking could lead to the single biggest improvement in someone’s health.

But a council boss said investments had to get the best returns for members of the Oxfordshire Pension Fund.

Martin Dockrell, spokesman for anti-smoking group Ash, said: “Councils have a duty to protect health policy from the vested interests of the tobacco industry.

“How can they discharge that duty if they are the biggest tobacco shareholders in the county?”

Steeple Aston mum-of-two Denise Cadd, who smoked from age 13 to 35, said: “I completely disagree with it from an ethical point of view. It is completely wrong.”

From next year, councils will get a key role on “health and wellbeing boards”, to take on responsibility for promoting good health.

Its priorities include preventing early death through smoking health checks and “support for behaviour change”.

Councils are members of the Oxfordshire Alliance on Smoking Issues, which aims to reduce the number of smokers.

Last month Dr Jonathan McWilliam, the county’s director of health said: “Stopping smoking is the single best thing that you can do to improve your health.”

The Oxford Mail asked the county council and NHS Oxfordshire to speak to Dr McWilliam but no comment was forthcoming.

The council has operated a no smoking policy at its buildings since 1989 and forbids smokers from adopting children because of “known health risks”.

Labour group leader Liz Brighouse said: “On one hand you’re having the responsibility to stop people smoking but on the other hand you are making money because people are smoking. Those two things don’t sit comfortably.”

Fund committee chairman David Harvey said tobacco investments had been “looked into at considerable length”.

He said: “We are following best practice by not discriminating either for or against tobacco companies. We look on it purely and simply as an investment.”

This is borne out by the fund’s investment in drug firms like GlaxoSmithKline, he said.

He added: “I don’t think we would invest in any company that knowingly broke the law or supported terrorism.”

County spokesman Paul Smith said tobacco is a common investment for councils and the fund is “obliged” to seek the best returns.

Ash says the law does not demand ethical concerns be snubbed “out of hand”. Official fund guidance says returns are the “principal concern” but “social, environmental and ethical considerations” must be taken.

Other firms the fund invests in include Tesco, Shell, Britvic, Morrisons, BSkyB, Vodafone and Bupa.

Its value has risen from about £800m five years ago and had given a “credible performance” amid economic turmoil, Mr Harvey said.

Oxfordshire County Council, the county’s four district councils, Oxford City Council and some town and parish councils contribute.

Teachers’ and NHS pension cash goes directly to The Treasury and is not invested.