Earlier in the day, Iranian Foreign Ministry spokesman Ramin Mehmanparast said that Iran is ready to start the nuclear talks " without delay," the semi-official ISNA news agency reported.

"About nuclear fuel swap and talks with Vienna group, we are ready to start the talks without delay and in the earliest time," Mehmanparast was quoted as saying.

The Vienna Group comprises the United States, France, Russia and International Atomic Energy Agency.

Talking to ISNA, Mehmanparast called the trilateral Istanbul meeting among Iranian, Turkish and Brazilian foreign ministers on Sunday "very positive" and said that "the meeting was a move forward and a positive act to materialize the Tehran declaration."

Turkey, Iran and Brazil signed an agreement on May 17, dubbed Tehran declaration, in which Iran committed itself to giving 1,200 kg of its 3.5 percent enriched uranium to Turkey in exchange for 20 percent enriched uranium it will receive from Western countries to be used as fuel in the nuclear research reactor in Tehran.

Later in the day, Mehmanparast criticized fresh EU sanctions against the country in an attempt to tighten pressures over Tehran to halt its nuclear program, the official IRNA news agency reported.

Sanctions "are not effective tools to stop nations from following their inalienable rights," he said, adding that "such measures will only help complicate situation."

"They (sanctions) also help move away from common understanding, " the spokesman was quoted as saying.

On EU's move, he maintained that Iran has already reiterated that opportunities can be used and climate of cooperation can be made through taking correct policies.

European Union (EU) foreign ministers on Monday approved tougher sanctions on Iran over Tehran's nuclear program, including measures to block oil and gas investment and curtail its refining and natural gas capability.

EU's restrictive measures, which went beyond UN sanctions imposed on June 9, followed a similar U.S. move.

British Foreign Secretary William Hague said Britain has been in recent weeks seeking an agreement in the EU on a strong package of sanctions implementing the UN Security Council Resolution 1929. London also wanted a message to Iran that it can not just walk away from negotiations and expects no further pressure.

The new sanctions include restrictions on banking and insurance, transport, and investment in new oil and gas fields or technical assistance to oil and gas development.

On July 1, U.S. President Barack Obama signed a new Iran sanction bill into law, which was described by him as "striking at the heart" of Iranian government's nuclear ability.

UN Security Council adopted last month a resolution on the Iranian nuclear issue, prohibiting Iran from investing abroad in nuclear and enrichment operations, imposing new restrictions on Iran's import of conventional arms and allowing the Iranian ships in the international waters to be checked.

Iran has reiterated that its nuclear program is aimed at civilian use.