Iran abusing ties with Russia: Russian source

MOSCOW (Reuters) - Iran is abusing Russia's stance on the country's nuclear program, Russian news agencies quoted "an informed source" in Moscow as saying.

"Unfortunately, the Iranians are abusing our constructive relations," news agencies quoted the source as saying.

The source added Iran "cannot play forever" on its good relations with Russia.

"It is unacceptable for us to have an Iran with a nuclear bomb or the potential to create one," the source said.

The comments were reported by Russia's three main news agencies. Senior government officials often brief the agencies anonymously to send messages to foreign governments.

The United States is pushing for tougher sanctions on Iran because it believes Tehran is trying to build a nuclear bomb, an allegation Iran has denied.

Russia has tried to soften the sanctions, arguing engagement with Iran is more productive than confrontation.