"A very big gap" remains between Western powers and Russia over the best way of resolving the crisis in Syria, but there are signs of a willingness to compromise on all sides, Prime Minister David Cameron has said.
His comment came after he joined US President Barack Obama and other European leaders in a concerted bid at the G20 summit in Turkey to persuade Russian president Vladimir Putin to co-operate with efforts to bring about a "transition" from the rule of Bashar Assad, a close Moscow ally.
In face-to-face talks with Mr Putin in the Turkish beach resort of Antalya - just 300 miles from the Syrian border - Mr Cameron urged him to turn Russia's firepower on the Islamic State (IS) terror group which posed a threat to countries around the world.
While Mr Putin insists that Russian air strikes are directed at "terrorists", the West accuses him of targeting the moderate opposition forces ranged against Assad.
But the Prime Minister - who has so far held back from seeking parliamentary approval to extend RAF air strikes from Iraq into Syria - acknowledged that "a few extra bombs and missiles won't transform the situation" and that a government with the confidence of all Syria's ethnic and religious communities was needed to bring about peace.
Two days after IS militants unleashed slaughter in Paris, Mr Cameron confirmed that UK intelligence and security agencies had thwarted seven smaller-scale attacks over recent months - one more than had previously been known about.
Speaking at a press conference on the second day of the summit Mr Cameron said that leaders of the G20 group of major economies had agreed "important steps" to counter the threat from terrorism.
These included measures to cut off financing for terror groups, counter extremist ideologies and propaganda and improve security at airports.
The countries had signed up to measures to bolster protection against the "threat of foreign fighters, by sharing intelligence and stopping them travelling", he said.
And he announced that Britain will co-host a donors' conference in London next year to raise "significant new funding" to address the refugee crisis in the Middle Eastern state and neighbouring countries.