Russia seized the initiative over Syria Wednesday after a diplomatic flurry that saw it host President Bashar al-Assad on his first foreign visit since 2011 and schedule talks involving the war's key players.

Assad met Vladimir Putin and thanked his Russian counterpart for launching air strikes against his opponents in Syria, with both leaders also agreeing during talks late Tuesday that political steps must follow military operations.

Moscow announced afterwards that Foreign Minister Sergei Lavrov would meet Friday with US Secretary of State John Kerry and their Turkish and Saudi counterparts to discuss Syria.

The talks between Putin and Assad focused mainly on military developments, with the Russian president pledging ongoing support but also urging a political solution to end the war, the Kremlin said.

Assad, who last visited Russia in 2008, had told Putin that the three-week-old Russian air war -- which has prompted an outcry in the West -- had helped to stop the spread of "terrorism" in his country.

The strikes are reported to have killed 370 people so far, a third of them civilians.

Russia says the campaign targets the extremist Islamic State group and others it describes as "terrorists".

But rebels and the West accuse Moscow of seeking to prop up Assad and of striking moderate and Islamist opposition forces rather than just Islamic State jihadists.

The Syrian Observatory for Human Rights said Wednesday at least 12 people including medical staff were killed when Russian warplanes struck a field hospital in the northwestern province of Idlib.

The clinic was run by the Syrian-American Medical Society, whose staff confirmed Tuesday's strikes had "severely damaged" the facility.

Putin's spokesman Dmitry Peskov said Assad's "working visit" was at the invitation of the Kremlin. The Syrian presidency said Wednesday that Assad had returned to Damascus.


- 'Syrians have last word' -



Russia's foreign and defence ministers also participated in a meeting between the two leaders.

Putin said Russia was ready to do all it could to help secure peace in Syria, which has been ravaged by the conflict that began with anti-government protests in March 2011.

More than 250,000 people have been killed and millions forced from their homes, sparking a mass migration of around four million refugees.

"We are ready to make our contribution not only during armed hostilities in the fight against terrorism but also during a political process," Putin said.

Assad also stressed the importance of "further political steps" and praised Russia for its military and political efforts, the Kremlin said.

"I need to say that the political steps which Russia has taken since the start of the crisis prevented the events in Syria from developing along a more tragic scenario," he said.

Putin emphasised that Syrians should decide their country's fate, a thinly veiled jab at the United States and other opposition backers who insist Assad must go in any peaceful settlement.


- New Syria talks Friday -



Putin discussed his talks with Assad in a string of phone conversations with Turkish leader Recep Tayyip Erdogan, Saudi King Salman, Egyptian President Abdel Fattah al-Sisi and Jordan's King Abdullah.

Saudi Arabia, Turkey and the United States are all key backers of the Syrian opposition and have criticised Moscow's military intervention in support of Assad's regime.

They have also long insisted Assad cannot be part of Syria's future, though some experts see a softening of the international line on whether the embattled leader could stay on during a political transition.

One of Assad's key allies, Iran, appeared less resolute in backing him on Wednesday, with deputy foreign minister Hossein Amir-Abdollahian saying it would not work to keep Assad in power "forever".

Speaking during a trip to Britain on Wednesday, Amir-Abdollahian said he was "very cognisant of his (Assad's) role in the fight against terrorism", but added: "We are not working for Assad to stay in power forever as president."

Iran has stood by Assad since the 2011 uprising against his regime, but has played down the extent of its on-the-ground support.

French President Francois Hollande has warned Russia against strengthening the position of Assad, "who is the problem, and cannot therefore be the solution".

Russia has carried out more than 500 air raids in Syria since its campaign began last month.

The Russian defence ministry said Wednesday its forces had hit 83 targets in Syria in the past 24 hours.

The strikes have been accompanied by a series of Syrian government ground offensives, in some places reportedly backed by an influx of Iranian forces, as well as Lebanon's Shiite Hezbollah movement.

The UN Office for the Coordination of Humanitarian Affairs said Tuesday that about 35,000 people had been displaced by one of the offensives, south of Syria's second city Aleppo.