MOSCOW, Jan. 16 -- Russian Foreign Minister Sergei Lavrov said Thursday that Iran was an integral part of the upcoming international conference on the Syria crisis.

"We believe that, in any case, the Iranian side must and will be an integral part of the efforts to settle the Syrian problem," Lavrov told reporters following talks with his visiting Iranian counterpart Mohammad-Javad Zarif.

"It is important to keep constructive cooperation between all participants of the process to preserve and strengthen a spirit of joint work formed in Geneva," he said.

Syrian Foreign Minister Walid al-Moallem is also in Moscow and will meet Lavrov and Zarif in trilateral talks later in the day.

However, Lavrov denied there are any tripartite project on Syria, saying "We have nothing to hide, and we don't have any hidden agenda."

Speaking of the negotiations on the Iranian nuclear program, Lavrov reiterated his earlier calls on all parties involved to refrain from any declarations and actions that might jeopardize the process.

Zarif confirmed Teheran was going to closely cooperate with Moscow over the Iranian nuclear problem.

"It is very important that the Iranian nuclear issue could be solved with Russia's facilitation," he told the news briefing, adding he believed progress would be achieved.

Later Thursday, the Iranian foreign minister will meet Russian President Vladimir Putin.