ISTANBUL, Turkey: Russian President Vladimir Putin met Turkish Prime Minister Recep Tayyip Erdogan in Istanbul on Monday on a trip focused on resolving sharp differences over the near 21-month conflict raging in Syria.
Protesters chanted anti-Putin slogans outside Erdogan's office and another demonstration was staged outside the Russian consulate in Istanbul before the two leaders began their meeting.
Putin's spokesman Dmitry Peskov told reporters that the Russian strongman will raise with Erdogan the planned deployment by NATO of Patriot missiles along Turkey's volatile border with Syria, the Interfax news agency reported.
The missile deployment "worries Russia and does not facilitate stability of the already fragile situation" in the region, Peskov said.
Turkey insists the US-made Patriots would be used for purely defensive purposes but Russia has warned that such a move could spark a broader conflict that would draw in the Western military alliance.
NATO's response is expected this week.
"Russia's position is consistent and absolutely transparent: one cannot support one side in the conflict, this cannot facilitate the settlement of the situation," Peskov was quoted as saying. "Active support of one side only provokes a conflict."
Putin was originally due to travel to Turkey in early October, but the visit was postponed because of tensions over the conflict in Syria and amid speculation about Putin's health.
Turkey, once an ally of the Damascus regime, has become one of its fiercest critics over the bloody crackdown on a rebellion that has developed into civil war and that monitoring groups say has killed more than 40,000 people.
But Moscow remains one of the few allies of Syrian President Bashar al-Assad, routinely blocking resolutions against his regime at the UN Security Council.
Last month, Erdogan said Russia held the key to the Syrian conflict, and that if Moscow took a "positive" stance in the Security Council it could push another key Damascus ally Iran to review its policies.
Russian-Turkish tensions came to a head in October when Turkey intercepted a Syrian plane en route from Moscow to Damascus on suspicion that it had military cargo, drawing an angry response from Russia.
In Istanbul on Monday, Putin and Erdogan will co-chair a high-level cooperation council meeting, a mechanism established between the two countries to foster ties.
Putin is also due to speak by telephone with Turkish President Abdullah Gul.
It is Putin's first trip outside Russia since he visited Tajikistan on October 5 and follows speculation that the normally globe-trotting leader is having health problems.
Official pictures handed out to the press for the Istanbul meeting showed the Russian leader in good health.
Russian media reports have said Putin is suffering from a back injury, caused possibly by a bad fall while playing his favourite sport judo or falling off his horse.
His aides admitted Putin was suffering from a light sports injury when he was spotted limping at an Asian summit in September, but have denied this had had any impact on his schedule.
Putin's absence from long distance travel has also dented his strongman image.
"I ask you not to be concerned. Not to worry. Everything is fine with his health," Kremlin chief of staff Sergei Ivanov said on Friday, quoted by Russian news agencies.
"He had a minor sports injury," Ivanov added. "No one is immune from sports injuries."
Despite their differences on some thorny political issues, Russia and Turkey enjoy growing trade and energy links. The trade volume between the two countries is expected to reach $35 billion by the end of this year.
Turkey depends on Russia for most of its natural gas and oil supplies. In 2010, Ankara struck a deal with Moscow to build the country's first nuclear power plant at Akkuyu in the southern Mersin province.
After the Istanbul meeting, both countries are expected to sign a number of agreements including a memorandum of understanding in the sphere of banking and finance.
At the demonstration outside Erdogan's office, police detained three protesters who were demanding that Russia apologise and compensate the Circassians for tsarist policies that drove members of the indigenous group from the Caucasus in the 19th century.