TEHRAN, Iran » Iran has proposed a new round of talks about its controversial nuclear program with the six world powers, the country’s top nuclear negotiator said Saturday.

Saeed Jalili said he has formally called on the six powers — the United States, Russia, China, Britain, France and Germany — to return to the negotiating table with Iran.

The invitation comes in the wake of new sanctions recently imposed by the West over Tehran’s uranium enrichment program, which is a potential pathway to making nuclear arms.

The last round of negotiations between Iran and the five permanent members of the U.N. Security Council plus Germany in January in Istanbul, Turkey, ended in failure.

The U.S. and some of its allies accuse Iran of using its civilian nuclear program as a cover to develop atomic weapons. Iran has denied the charge, saying the program is for peaceful purposes only and is geared toward generating electricity and producing medical radioisotopes to treat cancer patients.

"We formally declared to them (the intent) to return to the path of dialogue for cooperation," Jalili told Iranian diplomats in Tehran, according to the official IRNA news agency. Jalili did not say when or through what channel he issued the invitation.

However, Iran’s ambassador to Germany, Ali Reza Sheikh Attar, said earlier Saturday that Jalili was to send a letter soon to EU’s foreign policy chief Catherine Ashton to arrange a new round of talks.

There was no immediate comment from Brussels on Jalili’s reported offer.

But it is the latest signal from Tehran that the country appears to be feeling the toll of international sanctions.

The U.N. has imposed four rounds of sanctions on Tehran over the nuclear enrichment, and separately, the U.S. and the European Union have imposed their own tough economic and financial sanctions. Washington’s measures target exports of gasoline and other refined petroleum products to Iran and have banned U.S. banks from doing business with foreign banks that provide services to Iran’s Revolutionary Guard.

Last month, President Mahmoud Ahmadinejad acknowledged that the current penalties were impeding Iran’s financial institutions, saying, "our banks cannot make international transactions anymore."

And earlier in December, Iran reinstated an offer for U.N. nuclear agency officials to visit Tehran, though it did not say whether the International Atomic Energy Agency would be able to focus on suspicions that Iran is secretly working on nuclear arms — a key condition set by the agency.

The U.S. and Israel have not ruled out a military strike against Iran’s nuclear facilities if Tehran doesn’t stop its nuclear program.

But Jalili warned Tehran would make any aggressor regret a decision to attack Iran.

"We will give a response that will make the aggressor regret any threat against the Islamic Republic of Iran," Jalili said.