Small and medium-sized construction firms are most at risk from the effects of the euro, says the Construction Confederation.

Confederation economist Chris Nicholls said that large firms already working internationally were likely to be "relaxed" about using the currency, which came into force on 1 January.

However, he warned that firms that have not had previous experience of working overseas are vulnerable to foreign exchange risk as the value of the new currency fluctuates relative to sterling. "It is much more than just an extra accounting item. The impact is much greater," Nicholls said.

"Companies used to dealing in sterling will be asked to deal in euros for the first time. There are an increasing number of large UK-based companies, including British Steel, demanding that all transactions are in euros. Firms have to make a strategic decision on how they will deal with the foreign exchange risk." The confederation plans to step up its existing programme of seminars on the impact of the new currency for firms around the country. The confederation ran four of these last year.

Nicholls expects more enthusiasm for learning how to deal with the currency now it has come into force.

"We always anticipated that firms would be reactive rather than proactive," he said.

"People are only going to take this seriously once they get a customer asking for an invoice in euros." Contractors are expected to feel the full impact of the euro during the coming months.