"If I were in the Russian officials' shoes, I would be more careful in making remarks about this great neighbor of theirs [Iran]," Ahmadinejad said.

A trilateral agreement on uranium exchange was reached on Monday by Iran, Turkey and Brazil, setting out terms under which Iran will send 1.2 tons of its low-enriched uranium to get 120 kg of enriched to 20% uranium fuel. The swap will be carried out throughout the year on Turkey's territory.

However, the so-called Iran Six - the United States, Britain, France, Germany, China and Russia - discussed on Tuesday a draft Security Council resolution expanding sanctions against Iran over its nuclear program.

Iranian president said the agreement Iran signed with Turkey and Brazil left no place for "excuses."

"We expect our friends and neighbors to firmly defend this declaration [agreement] and not let a constructive interaction be hindered," he said adding that it was a sign of Iran's commitment to the nuclear Non-Proliferation Treaty (NPT) and the country's full cooperation with the International Atomic Energy Agency (IAEA).

Moscow and Beijing had long opposed U.S.-backed sanctions against the Islamic Republic over its controversial nuclear activities, insisting that the issue should be resolved by diplomatic means.

Iran, Brazil, and Turkey agreed that a letter be sent to the IAEA within one week to declare Iran is ready for the fuel exchange. After the letter is received by the IAEA, an agreement between Tehran and the agency must be drawn up and signed.

The head of the upper house's international relations committee, Mikhail Margelov, said Friday proposed new UN sanctions against Iran would not stop Russia from fulfilling its contract to deliver S-300 surface-to-air missile systems to the Islamic Republic.

Moscow signed a contract on supplying Iran with at least five S-300 systems in December 2005. However, the contract's implementation by Russia has so far been delayed.

The United States and Israel have called on Russia not to deliver the missiles to Iran.

The West is also concerned by Russia's role in helping Iran to build its first nuclear power plant in Bushehr. The head of the Russian State Atomic Energy corporation, Sergei Kiriyenko, said last week the plant will begin operating by late summer.