* Putin says "no shared approach" on Syria
* Energy, trade ties dominate talks
* Turkey seeks more Russian gas
By Evrim Ergin and Darya Korsunskaya
ISTANBUL, Dec 3 (Reuters) - Russia and Turkey agreed to differ on Monday on strategies to end Syria's civil war, highlighting how distant the prospects of a negotiated solution to the 20-month-old conflict are.
Russian President Vladimir Putin held talks with Turkish Prime Minister Tayyip Erdogan during a one-day visit to Istanbul aimed partly at ensuring differences over Syria do not damage a deepening trade and energy relationship.
"The positions of the Russian Federation and Turkey completely correspond regarding what has to be attained (in Syria), but as of yet no shared approach regarding methods of how to attain it has been reached," Putin told a joint news conference with Erdogan after the talks.
Turkey - worried about Syria's chemical weapons, a growing refugee crisis, and Syrian support for Kurdish militants - has been a major backer of the Syrian opposition and has led calls for international action against President Bashar al-Assad.
It sees Russia, one of Syria's closest allies, as key to quelling a conflict that has sent over a hundred thousand refugees fleeing to Turkish soil and stirred warnings of a sectarian war beyond Syria's borders.
"Our biggest wish is an immediate halt to the bloodshed and fighting in Syria, and we are taking steps to make sure our foreign ministers are carrying out extensive work with this aim," Erdogan told the news conference.
But Moscow has vetoed three U.N. Security Council resolutions aimed at putting pressure on the Syrian leader, blocking Turkish, Western and Arab efforts to provide U.N. support for the rebel forces trying to topple him.
As Syria's new opposition coalition consolidates, Russia has stepped up efforts to tell the world it is not on Assad's side, part of a bid to cast itself as a neutral player with an interest in peace alone. But it has shown no signs of shifting to join Western rivals in backing the rebels.
Turkish officials say Russia must be assured it does not stand to lose from the departure of Assad, who has been Moscow's chief Middle Eastern ally. Syria has been a major client for Russian arms and hosts a naval maintenance facility that is Russia's only military base outside the former Soviet Union.
Both sides have been careful to ensure their differences over Syria do not undermine a broader relationship governed by trade, Turkey's need for energy supplies and mutual security interests across an array of regional hotspots.
"Turkish-Russian relations have made significant progress in the last 10 years," Turkish Foreign Minister Ahmet Davutoglu said in a television interview ahead of Putin's visit.
"Nobody should dwell on a scenario in which tensions emerge between Turkey and Russia over Syria."
Russia provides nearly two thirds of Turkey's gas supplies and often ramps up its exports to the country during frequent cuts in Iranian gas supplies in the winter.
Erdogan said Turkey would continue to buy natural gas from Iran despite the prospect of tighter U.S. sanctions aimed at ratcheting up economic pressure on Tehran over its disputed nuclear programme.
Russian Energy Minister Alexander Novak, who was also in Istanbul, said on Sunday Russia was willing to increase gas supplies to Turkey - Gazprom's second-largest natural gas consumer after Germany - this winter if requested.
Turkish energy officials said Ankara, which usually buys around 30 billion cubic metres (bcm) of gas from Russia each year, had requested an additional 3 bcm from Gazprom ahead of an anticipated rise in energy demand in the winter months.
Gazprom clinched a long-term deal to export natural gas to private companies in Turkey last month, securing a growing market for the Russian gas export monopoly as it faces declines from its core consumers in the European Union.
The move followed a one-year impasse in gas trade between Gazprom and Turkish firms after state pipeline company Botas did not renew an expiring 25-year contract at the end of 2011 due to a pricing dispute. Business has continued in the meantime only on a short-term basis.
State-controlled Russian energy group InterRao meanwhile said it had reached a tentative agreement to complete the purchase of a power station in Turkey this year by buying the Turkish subsidiary of U.S. firm AEI.
Sources familiar with the matter say the deal had been held up for months amid tensions between Moscow and Ankara with Turkish government approval the last major hurdle.