BRUSSELS (AFP) - The European Union is carrying out a full security sweep of all its premises world-wide following claims that the United States spied on its offices in New York and Washington, a European Commission spokeswoman said on Monday.

"In light of the allegations, (European Commission chief Jose Manuel) Barroso has instructed the competent Commission services to proceed to a comprehensive ad hoc security sweep and check," the spokeswoman, Pia Ahrenkilde Hansen, said.

She said that all EU offices were "regularly swept" for bugs.

She also said the report published by German weekly Der Spiegel, based on revelations by fugitive US intelligence leaker Edward Snowden, was "disturbing" and demanded "full clarification".

"Clarity and transparency is what we expect from our partners and allies and this is what we expect from the United States," she said, amid calls from some EU officials for a harder reply.

Commission spokesman Michael Mann pointed out that the claims date back to 2010 and that the EU premises in New York and Washington had both been moved since then.

The claims "apparently relate to a historical situation," he said, pointing out that "a completely new security system" was now in place in both offices.

"We do always carry out security inspections when we move into new premises and we keep monitoring the security situation at all times," he said.