* Obama sticks to position despite Russia, China objections
* Obama and Putin talk one-to-one, aide says no change
* Leaders say will work together to spur economic growth
By Steve Gutterman and Matt Spetalnick
ST. PETERSBURG, Russia, Sept 6 (Reuters) - U.S. President Barack Obama defied pressure to abandon plans for air strikes against Syria at a summit on Friday which left world leaders divided on the conflict but united behind a call to spur economic growth.
Leaders of the Group of Twenty (G20) developed and developing economies, who account for 90 percent of the world economy and two thirds of its population, agreed that the economy was not out of crisis yet but was on the mend.
But Obama and Russian President Vladimir Putin remained far apart on Syria after a 20-minute one-on-one talk on the sidelines of the summit on Friday, following a tense group discussion on the civil war over dinner late on Thursday.
"There has been a long discussion with a clear split in the group," a G20 source said after the dinner in a Tsarist-era palace in Russia's former imperial capital, St. Petersburg.
Putin said he and Obama stood their ground and neither blinked but at least there was dialogue.
"We hear one another, and understand the arguments but we don't agree. I don't agree with his arguments, he doesn't agree with mine. But we hear them, try to analyse them," he said.
China's Xi Jinping also tried, unsuccessfully, to dissuade Obama from military action.
"A political solution is the only right way out for the Syrian crisis, and a military strike cannot solve the problem from the root," Xinhua news agency quoted Xi as saying. "We expect certain countries to have a second thought before action."
Washington says troops loyal to Syrian President Bashar al-Assad carried out a poison gas attack which killed over 1,400 people in rebel-held suburbs of Damascus on Aug. 21. Putin said the attack was carried out by the rebels in order to provoke outside military intervention against Assad.
Unable to win United Nations Security Council backing for military action because of the opposition by veto-wielding Russia, Obama is seeking the backing of the U.S. Congress.
He stuck to that position in St. Petersburg, despite a warning by U.N. Secretary General Ban Ki-moon about the need to find a political settlement to end the war.
"Every day that we lose is a day when scores of innocent civilians die," Ban said.
Ben Rhodes, Obama's deputy national security adviser, told reporters the president had "once again underscored the very high confidence that we have" of Assad's role in the attack.
Obama also told the G20 leaders that it was important to uphold international norms against chemical weapons and depicted the Security Council as paralysed.
Participants at the dinner said the tension between Putin and Obama was palpable but that they seemed at pains to avoid an escalation. Obama said credit was due to Putin for facilitating the long discussion of the Syrian crisis on Thursday night. .
Obama defended his position at the talks with Xi, whose country has veto powers on the Security Council.
Without referring to Syria, Obama said before meeting Xi: "Although there will continue to be some significant disagreements and sources of tension, I am confident that they can be managed."
He appeared isolated in St. Petersburg, despite France's support for military action, and the presence of allies such as Turkey and Saudi Arabia. But his actions suggested that winning the approval of Congress is his most important short-term goal.
Obama said most G20 leaders agreed that Assad launched the August 21 chemical weapons attack, but were divided over whether to use force in Syria without U.N. Security Council support.
Washington's ambassador to the United Nations, Samantha Power, made clear on Thursday that the United States had given up trying to work with the Council on the issue, and accused Russia of holding it hostage.
The dispute over Syria has deepened strains in U.S.-Russian ties, already difficult because of differences over human rights and Moscow's hosting of Edward Snowden, a spy agency contractor who revealed details of U.S. surveillance programmes. Putin said Obama had not requested Snowden's extradition on Friday, adding that it would be impossible anyway.
Obama planned to meet rights activists, including gay rights campaigners, to show support for civil society in Russia, where critics say Putin has clamped down on dissent in his third term.
But some invitees have declined to attend, citing what they said were repeated changes in the timing of the meeting. One added her voice to warnings against a military strike on Syria.
WORLD ECONOMY IMPROVING
The G20 achieved unprecedented cooperation between developed and emerging nations to stave off economic collapse during the 2009 financial crisis, but the harmony has since waned.
Despite their differences, the leaders agreed on a summit declaration that the global economy is improving although it is too early to declare an end to crisis.
The leaders stuck closely to a statement issued by G20 finance ministers in July that demanded monetary policy changes must be "carefully calibrated and clearly communicated".
"Our most urgent need is to increase the momentum of the global recovery, generate higher growth and better jobs, while strengthening the foundations for long-term growth and avoiding policies that could cause the recovery to falter or promote growth at other countries' expense," the leaders said.
Member states are at odds as the U.S. recovery gains pace, Europe lags, and developing economies worry about the impact of the Federal Reserve's plans to stop a bond-buying programme that has helped stimulate the U.S. economy.
The BRICS emerging economies - Russia, China, India, South Africa and Brazil - have agreed to commit $100 billion to a currency reserve pool that could help defend against a balance of payments crisis, but the mechanism will take time to set up.