Smoking will be banned in workplaces from 30 April

Firms could be fined up to £2,500 if smokers are caught on their premises.

The Federation of Small Businesses said owners will need to be vigilant and staff will have to be trained to deal with people flouting the ban.

FSB spokesman Harry McGimpsey said enforcing the regulations would prove a challenge for its members.

"We represent over 6,000 businesses, many of which are pubs, clubs, cafes and restaurants, whose owners will feel the full force of the ban," he said.

"While we support the health reasons behind it, which will on the whole benefit small businesses, some of the proposals will have cost implications for our members in terms of the signage required and preparing outside areas for customers who wish to smoke."