Russian President Vladimir Putin (L) shakes hands with US Secretary of State John Kerry during a meeting at the Kremlin in Moscow, Russia, July 14, 2016. [Photo/Agencies]

MOSCOW - US Secretary of State John Kerry met with Russian President Vladimir Putin about boosting military and intelligence cooperation against Islamic State and al Qaeda in Syria and told him that without "concrete, near-term steps," diplomatic efforts to end the war could not go on indefinitely.

Kerry met Putin for three hours at the Kremlin and their talks lasted until 1 a.m. local time on Friday.

The State Department said Kerry expressed concern about repeated violations of a cessation of hostilities by Syrian government. It said the two also discussed the need to need to increase pressure on groups like Islamic State and the Nusra Front, al Qaeda's affiliate in Syria.

Kerry "emphasized that absent concrete, near-term steps, diplomatic efforts could not continue indefinitely," a statement said, adding that discussions between Kerry and Russian Foreign Minister Sergei Lavrov on Friday were expected to explore initiatives in more detail.

On Thursday, the Washington Post published a leaked document it said Kerry would put forward in Moscow calling for intelligence sharing to identify leadership targets, training camps, supply lines and headquarters of the Nusra Front, al Qaeda's affiliate in Syria.

It said strikes against those targets could be carried out by US or Russian jets and expanded coordination would be channelled through a Joint Implementation Group based in the vicinity of the Jordanian capital, Amman.

Kerry declined to comment when asked about the document before leaving for Moscow.

Kremlin spokesman Dmitry Peskov said he would refrain from comment until Russian officials heard from Kerry, but that Russia in general favoured cooperation with the United States over Syria.

Putin said at the start of his meeting with Kerry that his last conversation with US President Barack Obama had convinced him that both sides were sincere in their efforts to find a solution in Syria.

"I hope after today's consultations you'll be able to advise him of the progress made and possible headway for us to make," he told Kerry.