The Government is facing a cross-party challenge from Sussex MPs to introduce a blanket ban on smoking in public places.

Ministers yesterday launched a consultation on plans to ban smoking in all enclosed public places, except pubs that do not serve food.

But Brighton Kemptown MP Des Turner and West Worthing MP Peter Bottomley are calling for the exemption to be dropped in legislation to be introduced later this year.

Their intervention came as speculation grew that the Government was considering a blanket ban only for the Department of Health to issue a categorical denial.

Medical leaders and public health campaigners have called for an outright ban, condemning the current plans as a "half-measure".

Public health minister Caroline Flint said the exemption had been requested during earlier consultations.

She said: "When we undertook consultation as part of the consultation it was clear people expected the Government to do more with legislation.

"But they also felt there should be some consideration of the fact that cigarettes are not illegal and there should be some element of free choice in all of this."

Under the proposed legislation, all enclosed public places and workplaces with exemptions for residential homes will be smoke-free by the end of 2007.

By the end of 2008, the ban will come into force for all licensed premises, except for private members' clubs and premises which do not serve food.

Between ten and 30 per cent of pubs are expected to be exempt.

Mr Bottomley, a Tory, and Labour's Dr Turner have backed a Commons motion which criticises the exemption for non-food pubs and calls for "comprehensive smoke-free legislation".