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

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

Iran's government instructed the country's nuclear organization on Sunday to start building five new plants and outline locations for another five within two months.

The diplomatic source said, however, that in line with Russia's position on the issue outlined by President Dmitry Medvedev, Russia would prefer Iranian "open and consistent cooperation" with the UN nuclear watchdog to allay concerns that Tehran was looking to build nuclear weapons.

"That is why we will not add any additional complications to the negotiations with threats of sanctions ... but we are obliged to bear in mind this possibility," the diplomatic source said.

MOSCOW, December 1 (RIA Novosti)