VIENNA – Iran offered Friday to negotiate with six world powers about its disputed nuclear program in a new bid to end growing concern that it could be used to produce weapons.

The move, following a hiatus of more than a year, was anticipated in the wake of an invitation to the Iranian leadership last month by chief EU envoy Catherine Ashton and following repeated statements by Tehran officials that they were ready for talks.

Ashton called the Iranian offer “a very important” development. Still, after eight years of Tehran refusing to halt uranium enrichment, despite U.N. Security Council sanctions, officials from the main countries trying to engage Iran expressed little hope of a breakthrough.

German Foreign Minister Guido Westerwelle said the readiness to talk should be viewed positively, “but out of the signals must come really concrete talks.”

Tehran has said its uranium enrichment is designed only to generate nuclear power. But it also could be used to manufacture weapons-grade uranium as fissile warhead material.

While Tehran argues that it has a right to enrich for peaceful purposes, international concern is building over Tehran’s nuclear secrecy and its refusal to allow the International Atomic Energy Agency to follow up on U.S. and other intelligence detailing alleged Iranian experiments geared at making nuclear arms.

Iran’s Supreme National Security Council said in a letter to the EU’s foreign policy chief that Iran is ready to hold talks after Nov. 10. With expectations modest, Washington appears keen to use the talks to demonstrate unity among the six powers — the U.S. Russia, China, Britain, France and Germany.