U.S. President Barack Obama on Friday met Russian gay rights activists after the G20 summit, in a symbol of U.S. support for the community amid a furore over an "anti-gay" Russian law.

Two gay rights activists were among a group of nine Russian civil society members Obama briefly met just before taking off from Saint Petersburg after the two-day G20 summit hosted by President Vladimir Putin.

Russian President Vladimir Putin on Friday said he held talks on Syria with U.S. President Barack Obama on the sidelines of the G20 summit but confirmed the meeting did not end their differences on the conflict, as the American leader said he knew convincing the U.S. Congress to back military action against Damascus would be a "heavy lift."

"We spoke sitting down... it was a constructive, meaningful, cordial conversation. Each of us kept with our own opinion," Putin told reporters, saying the meeting lasted 20 to 30 minutes.

Russian President Vladimir Putin discussed the situation in Syria with British Prime Minister David Cameron early on Friday, Putin's spokesman said.

Cameron and Putin met on the sidelines of the G20 summit in Saint Petersburg after discussing the Syrian crisis over dinner with other world leaders and watching a cultural show that ended around 2:00 am (2200 GMT).

Pope Francis on Thursday appealed to leaders gathering for a G20 summit in Russia to find a peaceful solution to the Syria crisis, warning against "futile pursuit of a military solution."

"To the leaders present... I make a heartfelt appeal for them to help find ways to overcome the conflicting positions and to lay aside the futile pursuit of a military solution," Francis wrote in a letter to Russian President Vladimir Putin who is hosting the G20 summit.

U.S. President Barack Obama arrived on Wednesday in Saint Petersburg for the G20 summit in Russia, where officials said he would argue his case for military action against the Syrian regime over an alleged chemical weapons attack.

With a serious expression, Obama jogged down the steps off his Air Force One plane which touched down at Saint Petersburg's Pulkovo airport ahead of the opening by Russian President Vladimir Putin of the summit later in the afternoon.

Russian President Vladimir Putin said Wednesday U.S. intelligence leaker Edward Snowden, who received asylum in Russia, is a "strange guy" who condemned himself to a difficult fate.

"You know, I sometimes thought about him, he is a strange guy," ex-KGB spy Putin said in an interview with state-run Channel One television.

President Vladimir Putin warned the West against taking one-sided action in Syria but also said Russia "doesn't exclude" supporting a U.N. resolution on punitive military strikes if it is proved that Damascus used poison gas on its own people.

In a wide-ranging interview with The Associated Press and Russia's state Channel 1 television, Putin said Moscow has provided some components of the S-300 air defense missile system to Syria but has frozen further shipments. He suggested that Russia may sell the potent missile systems elsewhere if Western nations attack Syria without U.N. Security Council backing.

Israel on Tuesday launched a missile over the Mediterranean Sea in a joint exercise with the United States which came as Washington mulls long-range strikes against Syria.

Speculation mounted after the missile firing at 0615 GMT, with Russia's defense ministry, quoted by news agencies, saying its early warning system had detected the launch of two ballistic missiles from the central Mediterranean fired towards the sea's eastern coastline, on which Syria lies.

Russia is totally unconvinced by evidence presented by the United States and its allies of an alleged chemical attack outside Damascus that the West says was perpetrated by the Syrian regime, Foreign Minister Sergei Lavrov said Monday.

Moscow vehemently opposes U.S.-led plans for military action against the regime of Bashar Assad in response to the alleged attack, even though the timetable has now been put back by President Barack Obama's decision to put it to Congress.

Russian President Vladimir Putin on Saturday dismissed as "nonsense" claims that the Syria regime has used chemical weapons and demanded that the United States provide proof.

Speaking after the United States released an intelligence report, Putin rejected communications intercepts as evidence, saying that they cannot be used to take "fundamental decisions" like using military force on Syria.