Catherine Ashton
Catherine AshtonReuters

Chief negotiators for the EU and Iran agreed on Thursday to hold more talks about Tehran's nuclear work, Reuters reported, but the European Union gave no sign progress was imminent in the dispute.

Six world powers, represented by EU foreign policy chief Catherine Ashton, have sought to persuade Iran to scale back its nuclear program through intensifying economic sanctions and diplomacy.

They have failed to reach a breakthrough in three rounds of talks since April. Neither side has been willing to break off talks because of concerns, in part, that this could lead to a new war in the Middle East if Israel attacked Iran.

“I ... have explored diplomatic ways to resolve international concerns about Iran's nuclear program,” Ashton said in a statement quoted by Reuters, after a phone conversation with Iran's chief negotiator Saeed Jalili.

“I impressed the need for Iran now to address the issues we have raised in order to build confidence. I proposed, and Dr. Jalili agreed, that we talk again after further reflection at the end of the month,” she added.

In June, talks in Moscow between Iran and the six - the United States, Russia, China, France, Germany and Britain - hit an impasse.

At the core of the discussions are Iranian efforts to enrich uranium to 20 percent fissile purity, an advance that would bring it close to acquiring weapons-grade material.

World powers are demanding that Tehran abandon such production, ship stockpiles out of the country and close an underground facility where high-grade enrichment takes place. Tehran has refused to meet the demands unless economic sanctions are lifted.

Last month, Iran accused the world powers of dragging their feet in negotiations over its nuclear activities.

Foreign ministry spokesman Ramin Mehmanparast asserted that if the powers ignored Iran's nuclear “rights” and failed to bargain on equal terms, the negotiations could lead to an “impasse.”

“All that can reinforce the idea that there is a desire to drag out the negotiations or prevent their success,” he said, adding that “illogical, irresponsible” Western sanctions “amount to a hostile act against Iran and its national interests.”

Sanctions pressure increased this week when the U.S. Congress overwhelmingly passed a new package of sanctions against Iran that aims to punish banks, insurance companies and shippers that help Tehran sell its oil.

On Tuesday, President Barack Obama announced U.S. sanctions against foreign banks that help Iran sell its oil, specifically citing China's Bank of Kunlun and an Iraqi bank.