Vladimir Putin has hailed the "efficient and close" relationship between Russia and Turkey's militaries, as he hosted Turkish leader Recep Tayyip Erdogan for talks about Syria.

Relations between the countries – which back opposing sides Syria's ongoing war – have been tumultuous. Ties became strained in 2015 after Turkey's military shot down a Russian warplane near the country's border with Syria.

More recently, interactions between the countries have appeared to warm, with the nations brokering a ceasefire in December that significantly diminished fighting in the country.

Together they have also organised two rounds of talks between Syrian President Bashar al-Assad and his opponents, with a third round of discussions set to start in the coming days.

After concluding his meeting with Mr Erdogan, the Russian leader hailed what he called “efficient and close contact” between their militaries and intelligence agencies around Syria.

He told a news conference it was mostly “Russia and Turkey that have made a major contribution not only to securing a ceasefire between Syrian government forces and the armed opposition, but also to launching direct, concrete talks” between them.

He added that he wanted to "express cautious optimism" that they could "move to a fully-fledged political resolution” with other major players like the US.

Despite their opposite sides in the Syrian conflict, the two countries have closely coordinated their operations against Isis in the country.

Earlier in the week, chief military officers from Russia, the US and Turkey met in the Turkish city of Antalya to negotiate measures that would prevent future accidental deaths of each other's troops.

The talks also focussed on how to temper mistrust between Turkish-backed Syrian opposition forces, US-backed Kurdish forces and Russian-allied Syrian government forces, which are all fighting their way towards the Isis group's de facto capital, Raqqa.

Asked whether Moscow and Ankara shared the idea that Syria and Iraq should be preserved within current borders, Mr Putin spoke of “the complex situation” and “contradictions” in the Syria peace talks.

But he insisted that preserving Syria's territorial integrity is a “necessary condition for the full-scale peace settlement in this country”.