The European Union earlier added more than 100 firms to a blacklist of companies hit by an assets freeze, in what it said was a bid to jumpstart international talks aimed at convincing Iran to halt its nuclear activities.

"The United States welcomes the decision of the European Union to expand its sanctions on Iran," said White House spokesman Jay Carney, in a statement issued in Dublin during President Barack Obama's visit to Ireland.

"So long as Iran refuses to fulfil its international obligations, the international community will respond by continuing to hold Iran accountable, implement fully all UN Security Council resolutions, and aggressively counter Iranian proliferation activities.

"The United States remains fully committed to the peaceful resolution of international concerns regarding Iran's nuclear programme."

Among firms added to the list is the European-Iranian Trade Bank (EIH), a German-based Iranian-owned concern, along with five individuals who will face an assets freeze and EU travel ban, a diplomat said.

An official in Berlin told AFP last week that "evidence pointing to the EIH's involvement in (nuclear) proliferation has multiplied and become tangible."

The United States, Britain, France, Germany, China and Russia have engaged in on-and-off talks with Iran aimed at halting its uranium enrichment programme.

Western powers fear that Iran is seeking to build a nuclear bomb, but Tehran denies the charge, insisting that it is merely trying to meet its people's energy needs.

The EU and the United States have slapped unilateral sanctions on Iran on top of four sets of punitive measures imposed by the UN Security Council.

Copyright AFP (Agence France-Presse), 2010