Russia will back sanctions against Iran over its controversial nuclear program if consensus is reached internationally, an unnamed Russian diplomatic source said on Tuesday.

"If there is a consensus on sanctions, Russia will not remain in isolation," said the source, commenting on Tehran's plans to build 10 new uranium enrichment facilities. "We will not stay aloof," he added.

However, "it is not the imposing of sanctions that we would consider more preferable," said the source, "but a more open and coherent cooperation between Iran and the International Atomic Energy Agency (IAEA) and clearer steps (on the part of Tehran) in response to those concerns."

The source said concerns over Iran's nuclear program had become increasingly unjustifiable, and Tehran's new construction plans would not add optimism to ongoing negotiations.

"Such declarations do not add optimism to the already complicated negotiations with Iran," he said, while emphasizing the "key role" of the IAEA's conclusions.

Nonetheless the source downplayed Tehran's new construction plans as "intentions" so far.

"Let us see if they fulfill their intention. Statements of the kind are bad for the general atmosphere," said the diplomat.

The source also said there was no plan of imposing sanctions on Iran in the near future. Sanctions are "not a matter of the coming hours or weeks," but "we must think about this," said the source.

Russia on Monday voiced serious concerns over Iran's new construction plans, said the Interfax news agency, citing a foreign ministry source.

The IAEA board of governors passed a resolution on Friday, calling for the "full cooperation" of Iran to clarify all outstanding issues involving its nuclear program.

The Iranian government ordered the country's Atomic Energy Organization to build 10 new uranium enrichment sites in defiance of the IAEA resolution.

Iran has been repeatedly urged to respond to an IAEA-brokered draft deal, which called for shipping some 70 percent of Iran's enriched uranium abroad in exchange for fuel rods for research use.

It has been agreed by the other parties involved in negotiations with Tehran, including the United States, Russia and France.

Tehran is at the center of an international dispute over its nuclear ambitions. Western powers suspect Iran of attempting to build nuclear weapons, while Tehran says its nuclear program is aimed at generating nuclear energy for civilian purposes.