Ministers are under renewed pressure from Labour MPs to introduce a total ban on smoking in public places.
The government wants to ban smoking in enclosed spaces
The Health Bill, which introduces a partial ban on smoking in public places in England, has cleared its first hurdle in the House of Commons.
But ex-health secretary Frank Dobson, who dubbed the bill "half-baked and half-hearted", warned that it must be amended later to implement a total ban.
Health Secretary Patricia Hewitt says the bill strikes the right balance.
Lib Dem Paul Burstow says research shows a total ban could save 200 people from dying due to passive smoking.
Ms Hewitt, who is believed to have wanted a total ban but backed down after strong opposition from her predecessor John Reid, said she believes a total ban will ultimately happen.
Chief Medical Officer Sir Liam Donaldson said last week he had considered resigning after the government ignored his advice for a total ban.
Professor Alex Markham, chief executive of Cancer Research UK, said the partial ban plan showed the government was "completely out of touch with the population".
Mr Dobson said the government was knowingly widening the "health gap" between rich and poor because a partial ban was bad for working class people.
"Pubs, clubs and bars serving booze but no food are mainly located in poor neighbourhoods and serve working class people," he said.
"So this partial ban would be good for the health of middle class people but bad for the health of working class people."
But opening the second reading debate of the bill, Ms Hewitt said: "In framing this legislation ... we are striking a balance between two extremes: an over-prescriptive state on the one hand and on the other an irresponsibly laissez-faire government.
"We are responding to the clear wish of the public on the one hand to be protected from other people's smoking in public places - particularly in restaurants - and on the other hand to allow people who want to have a cigarette with a drink to do so."
Shadow health secretary Andrew Lansley accused ministers of "excessive" interference.
He said the Tories would have preferred a "self regulatory solution" to provide more smoke-free environments.
Labour MP Andrew Mackinlay said the government could face a second Commons defeat on the issue, just two weeks after it lost a crucial vote on the Terrorism Bill.
"They aren't reading the political tea-leaves because there is a majority in this House for a complete ban," he said.
The bill also sets out a range of measures to protect patients from MRSA infections, and a repeat of the Shipman murders.
It also includes details of a new hygiene code for hospitals and reform of controlled drugs management.