LONDON, Feb 2 (Reuters) - Britain's Labour Party on Monday said businesses' biggest worry about an upcoming election was that it could lead to an exit from the European Union, rejecting criticism from a chief executive who said a Labour win would be a "catastrophe".
On Sunday Stefano Pessina, the head of international pharmacy chain Wallgreens Boots Alliance Inc. said the left-leaning party's policies were unhelpful to businesses and that a Labour government after the May election would be a "catastrophe" for the country.
Pessina also said that it would be a "big mistake" for Britain to leave the EU.
Labour's economic spokesman Ed Balls, the man who would become finance minister if they win the election, seized upon that comment, turning the fire on Prime Minister David Cameron's Conservatives by saying the real danger for businesses came from Cameron's plan to hold a referendum on Britain's EU membership.
"The only tangible thing he (Pessina) says ... was his fear is of Britain leaving the European Union," Balls told BBC radio.
"That's what I hear from businesses up and down the country all the time ... when I was in Washington a couple of weeks ago, the big fear of American policymakers is a Tory (Conservative)government taking Britain out of Europe."
Cameron has promised the referendum by 2017 to win back Eurosceptic voters who have defected to the anti-EU UK Independence Party (UKIP). He wants to negotiate reformed ties with Europe and, if successful, says he would campaign for Britain to stay in the bloc.
Labour hold a thin lead over the Conservatives in opinion polls, but are ranked below their rivals on economic competence, something which is consistently shown to be high on the list of key issues for voters ahead of the ballot. (Reporting by William James; editing by Guy Faulconbridge)