Former French president Nicolas Sarkozy on Thursday urged the West not to "isolate" Russia, as international powers including Moscow gathered for crunch talks in Vienna on the future of Syria.
Moscow's relations with the West have plunged to a post-Soviet low over the annexation of Ukraine's Crimea peninsula and Russia's involvement in the conflict in eastern Ukraine.
Sarkozy met Russian President Vladimir Putin at his residence outside Moscow on Thursday after addressing the Moscow Institute of International Relations.
He told the institute it "does not make sense to isolate Russia" in the face of complex challenges like the crisis in Syria.
With the Islamic State (IS) jihadist group threatening the region, he said the US-led coalition must act together with Syria and its backers Iran and Russia.
Russia has waged an aerial bombing campaign for nearly a month supporting the Syrian army, earning criticism from Washington, which accuses Moscow of targeting moderate opposition groups opposed to Assad's rule.
"We must merge the two coalitions into one," Sarkozy said.
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"Without Russia, one cannot meet the great challenges of this world," he said, adding that the global role of Putin is "more positive than negative, despite our differences."
After the speech Sarkozy, French president from 2007 to 2012, met Putin for informal talks, where they reminisced about past ties.
"We had disagreements but could also find ways to a good compromise," Sarkozy told Putin as the two sat around a fireplace.
"The world needs Russia," he said, calling for mutual cooperation. "Russia and Europe are able to work together... To talk, listen and respect, that is the future for Russia and France," Sarkozy said.
Western sanctions on Russia over Ukraine led to Paris cancelling a deal to sell two warships to the Russian navy for an estimated $1.3 billion, a move that Moscow said was done due to pressure from Washington.
"I am so happy to see you, Nicolas," Putin said, using the informal word for "you" to address Sarkozy.
"So many things have happened in Europe, the world and our bilateral relations" over the past year, Putin said.
Sarkozy was in Moscow with a delegation of his party The Republicans as he pushes himself as a candidate for France's 2017 presidential election.