Under the new legislation, currently moving through Parliament, smoking will be banned in England in enclosed public places as well as workplaces, including restaurants, pubs and private clubs from summer 2007.
Health Minister Lord Warner has confirmed that ministers will now also consider whether to use powers set out in the Health Bill to outlaw smoking in other places where there is a "close grouping of people".
He told peers: "These will be places that will not be enclosed or substantially enclosed but where there is a risk of harm from second-hand smoke due to the inevitable close grouping of people.
"Examples might be sports stadiums, bus shelters and entrances to public buildings or workplaces."
However, under pressure from critics claiming the proposal was too sweeping, ministers have changed the wording of legislation to promise the ban will spread to outdoor spaces only if there is a "significant risk" that people will be exposed to "significant quantities of smoke".
A spokeswoman for the Department of Health said there would be consultation over the coming months on how an enclosed space would be defined by law. The Government will also consult on whether to extend the ban to other places. She added that any such extension would not happen until after it was seen how the enclosed space ban worked.
Under the new legislation there will be fines for smokers lighting up in banned areas. Failing to stop people smoking in banned areas will attract penalties of up to £2,500.