The British Agencies for Adoption and Fostering (BAAF), which issued the guidance, warned that children with respiratory problems are also at risk. It said there could be exceptions; for instance if a prospective parent was a member of the child's own family, or if no other suitable parents were available.
But Tim Yeo, Under-Secretary of State for Health, criticised the 'dogma' and 'ideology' behind the advice that couples who smoke should generally not be allowed to foster or adopt babies under two.
Smoking was only one consideration in selecting parents, he said. 'It would be quite wrong for a child to be denied the chance of a loving home solely because there is a smoker in the household. There is no room for dogma or ideology in any aspect of adoption.'
Mr Yeo added: 'The interests of the child are the overriding consideration in all cases and each case must be judged on its merits, using common sense and compassion. The overall health of prospective adopters and the possible influence on the lifestyle, on the health of the child is one consideration when deciding if they are suitable to adopt.'
However, Christine Hammond, director of BAAF, said it was not advising that a child should never be placed with a smoker. 'But there are four to five couples for every baby and for every suitable couple who smokes there will be a suitable couple who are non-smokers.
'Evidence suggests that there is significant risk from passive smoking. One Swedish study said that when mothers smoked more than 10 cigarettes a day the risk of cot death was three times greater than among non-smoking mothers,' she said.
'We are advising agencies to balance the risks and to choose the couple whose lifestyle is most likely to serve the best interests of the child.'
Cot death rates have fallen from 2 per 1,000 live births, which was static for many years, to 1.3 in 1991 and another fall is expected for 1992. One of the reasons for this was the advice to lay babies on their backs. Cot deaths are still the largest single cause of death in infants aged one week to two years.
Smoking is a risk factor for cot death. When mothers smoke more than 20 cigarettes a day it is increased five times, Joyce Epstein, secretary ageneral of the Foundation for the Study of Infant Deaths, said.
Dr Ann McNeill, manager of the Health Education Authority's smoking programme, said that BAAF's advice was 'a natural extension of the information which has been coming out on the dangers of passive smoking'.
Leading article, page 27