A ban is expected to be put in place by spring 2006

Dr Mac Armstrong said the ban would deliver a "priceless benefit" in saved lives and less ill-health.

The bill is currently the subject of stage one hearings by MSPs on the health and finance committees.

If passed, it would outlaw smoking in almost all enclosed commercial premises in Scotland by spring next year.

Environmental health officers would be able to search premises and employers or managers would face �2,500 for breaching the ban or �1,000 for not displaying no-smoking signs.

Those lighting up could be hit with a �1,000 penalty.

'Financial impact'

About �2m will be spent next year publicising the ban and marketing Scotland as a smoke-free country, while those trying to quit will get more help.

The Scottish Licensed Trade Association (SLTA) claims the outright ban proposed by ministers would cost 2,300 jobs initially, cut annual profits by �86m and force more than 140 pubs to close.

Executive-commissioned analysis of current smoking bans elsewhere in the world, published in December, gave a "central estimate" for the economic impact of a ban on Scotland's hotels, restaurants and bars of a �110m increase in revenues.

However that report also included a "worst case" estimate of a �63m loss to the industry as well as an upper level benefit, suggesting a gain of �281m.

The bottom line here isn't financial at all, it's human and the real benefit is priceless Dr Mac Armstrong Chief medical officer

The SLTA, which will address the finance committee on Tuesday, branded that international review as "incomplete, irrelevant and rushed".

In a written submission, SLTA president Alistair Don said licensees did not oppose new curbs on lighting up, but that they had been "alarmed by the lack of any in-depth study of the potential financial impact" of a ban.

Mr Don is urging MSPs, who could amend the legislation at stages two and three, to consider the proposals south of the border, where the ban would not cover pubs not serving hot food.

'Terrible toll'

However, Dr Armstrong urged MSPs to retain the executive's scheme, saying it would bring "far and away the most important improvement" in Scotland's health for a generation.

He said: "There has been a lot of talk in recent weeks about businesses losing money and profits being hit.

"But the bottom line here isn't financial at all, it's human and the real benefit is priceless."

Dr Armstrong said smoking was wreaking "a terrible toll", with 35 Scots dying before their time every day due to smoking-related diseases.

He added: "Up to 2,000 lives could be saved every year by ending smoking in enclosed public places. And let's not forget the substantial knock-on effect which will see fewer people smoking and people smoking less."