Medvedev said on Thursday he wanted an explanation from Tehran over the "military components" of Iran's nuclear program.
"I would like to say that Iran is our rather active trading partner and has been tested by time, but that does not mean we are indifferent to the way Iran is developing its nuclear program and we are not indifferent to how the military components of the corresponding program look," he said.
"In this respect, we are waiting for the appropriate explanations from Iran," he said.
"The information we are getting — it comes from open channels and reports from the secret services — shows these programs are developing ... and Iran must find the courage to start fully fledged cooperation with the international community," Medvedev said.
Iran's opaque nuclear program has been a tricky issue for Russia, which is uneasy about threatening decades of political and trade ties. However, Russia lately has shown increasing frustration with Iran and backed the new round of UN sanctions imposed last month.
The US administration of President Barack Obama has made a priority of winning Russian support for a tougher line toward Iran, which Western countries suspect of seeking nuclear weapons. Iran says its nuclear program is peaceful.
Russia, which is building Iran's first nuclear power plant, voted to tighten sanctions against Iran last month in the UN Security Council, and Medvedev said this week Tehran was gaining the ability to make nuclear weapons.
Russia tells Iran: come clean over weapons work
YEKATERINBURG, Russia, July 15 : Russian President Dmitry
