Sir Clive Thompson, President of the CBI and chief executive of service firm Rentokil Initial, said that industry preparations for the euro "would be helped by the government setting a date" for entry.

Speaking at the end of the CBI's annual conference, he said that many small businesses would not make the necessary preparations "unless they know it will happen."

And he warned that inward investment by multi-nationals could suffer if uncertainty about British membership continued.

Yesterday Chancellor Gordon Brown told the conference that the government was setting up a national changeover plan as from January which would set out the practical steps the UK would need to take if it decided to join the euro.

In less than two months, the euro will become the single currency for 11 EU countries, with only the UK, Denmark, Sweden, and Greece remaining outside.

Call for open debate





He warned business that without the euro, the UK could face increased exchange rate instability and a return to a boom-and-bust economy.

Mr Turner said that the CBI wanted an open debate on whether to join a single currency, and it would conduct a major survey of its members in the first half of next year.

But he criticised the "baggage of labour market harmonisation which some people in Europe mistakenly believe should accompany monetary union."

His remarks also focused on the need for UK firms to raise their productivity, a theme expected to be emphasised by the government in the pre-Budget statement.

He said that while firms had the main burden of innovation, government could help by improving the skills of the workforce and providing tax incentives for capital investment.