Vladimir Putin , Recep Tayyip Erdogan and Ebrahim Raisi meet before a summit in Tehran, Iran, on Tuesday. Reuters

Putin also praised his talks with the presidents of Iran and Turkey, speaking after a three-way summit on the Syrian conflict overshadowed by Moscow's intervention in Ukraine.

Putin said the Syria summit in Tehran was "truly useful and rather substantial," describing the atmosphere as "business-like and constructive."

Speaking after meeting with leaders of Turkey and Iran in Tehran, Putin said the countries agreed to continue consultations on Syria.

Putin travelled abroad for only the second time since ordering Russia's invasion of Ukraine in order to attend the gathering that also involves Turkish President Recep Tayyip Erdogan.

Tayyip Erdogan speaks with Vladimir Putin as Ebrahim Raisi listens, as they arrive for a joint news conference in Tehran.  AFP

The summit, which got underway shortly after the supreme leader's meeting with Putin, comes days after US President Joe Biden visited the Middle East for the first time in his presidency.

The summit, hosted by Iran's conservative President Ebrahim Raisi, is the first since he took office last year and is ostensibly aimed at ending more than 11 years of conflict in Syria.

All three countries are involved in the conflict, with Iran and Russia supporting Syria's President Bashar Al Assad and Turkey backing rebel forces.

Ahead of the trilateral presidential meeting, Khamenei met separately with Putin and Erdogan, calling for stronger "long-term co-operation" with Moscow, according to a statement on his official website that noted both Moscow and Tehran are afflicted by Western sanctions.

Describing such ties as "deeply beneficial to both countries," the supreme leader called for contracts and understandings in hydrocarbons to be "followed up and implemented fully."

Prior to his visit, the National Iranian Oil Company and Russia's Gazprom signed a memorandum of understanding "worth about $40 billion," according to Iran's oil ministry's official news agency, Shana.

Syria's Kurds, Ukraine grain

Erdogan, speaking at the opening of the summit, urged both Russia and Iran to back its fights against "terrorism" in Syria. He had earlier told a joint news conference that Kurdish militias caused "great trouble" for both Iran and Turkey.

Turkey has launched waves of attacks on Syria since 2016, targeting the Kurdish militias as well as Daesh group and Asad loyalists.

Erdogan has repeatedly threatened to launch a new offensive against the Kurds, but Khamenei told the Turkish leader in their pre-summit meeting it would be "detrimental" for the region. He called for the issue to be resolved through dialogue between Ankara, Damascus, Moscow and Tehran.

"The timing of this summit is not a coincidence," Russian analyst Vladimir Sotnikov said. "Turkey wants to conduct a 'special operation' in Syria against the Kurds just as Russia is implementing a 'special operation' in Ukraine."

Putin and Erdogan also held a bilateral meeting where the Russian president said he wanted to "thank" his Turkish counterpart for progress on talks over Ukraine's grain, according to the Kremlin.

Russia's war on Ukraine has massively hampered shipments from one of the world's biggest exporters of wheat and other grain, sparking fears of global food shortages.

Turkey — a Nato member on speaking terms with both Russia and Ukraine — has spearheaded efforts to resume the grain deliveries.

Erdogan has for months been offering to meet Putin in a bid to help resolve heightened global tensions.

"I want to thank you for your mediation efforts" Putin told Erdogan during the bilateral meeting, according to comments released by the Kremlin.

"We have moved forward," Putin said, while adding "not all issues have yet been resolved."

EU foreign policy chief Josep Borrell warned on Monday that Russia's blockade of Ukrainian ports threatens supplies to countless thousands vulnerable to starvation.

malisation in Syria: Putin

Russian President Vladimir Putin said on Tuesday that Russia, Iran and Turkey were committed to continue efforts on "normalisation" of the situation in Syria.

Putin also praised his talks with the presidents of Iran and Turkey, speaking after a three-way summit on the Syrian conflict overshadowed by Moscow's intervention in Ukraine.

Putin said the Syria summit in Tehran was "truly useful and rather substantial", describing the atmosphere as "business-like and constructive."

Speaking after meeting with leaders of Turkey and Iran in Tehran, Putin said the countries agreed to continue consultations on Syria.

Putin travelled abroad for only the second time since ordering Russia's invasion of Ukraine in order to attend the gathering that also involves Turkish President Recep Tayyip Erdogan.

The summit, which got underway shortly after the supreme leader's meeting with Putin, comes days after US President Joe Biden visited the Middle East for the first time in his presidency.

The summit, hosted by Iran's conservative President Ebrahim Raisi, is the first since he took office last year and is ostensibly aimed at ending more than 11 years of conflict in Syria.

All three countries are involved in the conflict, with Iran and Russia supporting Syria's President Bashar Al Assad and Turkey backing rebel forces.

Ahead of the trilateral presidential meeting, Khamenei met separately with Putin and Erdogan, calling for stronger "long-term co-operation" with Moscow, according to a statement on his official website that noted both Moscow and Tehran are afflicted by Western sanctions.

Describing such ties as "deeply beneficial to both countries," the supreme leader called for contracts and understandings in hydrocarbons to be "followed up and implemented fully."

Prior to his visit, the National Iranian Oil Company and Russia's Gazprom signed a memorandum of understanding "worth about $40 billion," according to Iran's oil ministry's official news agency, Shana.

Syria's Kurds, Ukraine grain

Erdogan, speaking at the opening of the summit, urged both Russia and Iran to back its fights against "terrorism" in Syria.

He had earlier told a joint news conference that Kurdish militias caused "great trouble" for both Iran and Turkey.

Turkey has launched waves of attacks on Syria since 2016, targeting the Kurdish militias as well as Islamic State group jihadists and Assad loyalists.

Erdogan has repeatedly threatened to launch a new offensive against the Kurds, but Khamenei told the Turkish leader in their pre-summit meeting it would be "detrimental" for the region. He called for the issue to be resolved through dialogue between Ankara, Damascus, Moscow and Tehran.

"The timing of this summit is not a coincidence," Russian analyst Vladimir Sotnikov said. "Turkey wants to conduct a 'special operation' in Syria against the Kurds just as Russia is implementing a 'special operation' in Ukraine."

Putin and Erdogan also held a bilateral meeting where the Russian president said he wanted to "thank" his Turkish counterpart for progress on talks over Ukraine's grain, according to the Kremlin.

Russia's war on Ukraine has massively hampered shipments from one of the world's biggest exporters of wheat and other grain, sparking fears of global food shortages.

Turkey — a Nato member on speaking terms with both Russia and Ukraine — has spearheaded efforts to resume the grain deliveries.

Erdogan has for months been offering to meet Putin in a bid to help resolve heightened global tensions.

"I want to thank you for your mediation efforts" Putin told Erdogan during the bilateral meeting, according to comments released by the Kremlin.

"We have moved forward," Putin said, while adding "not all issues have yet been resolved."

EU foreign policy chief Josep Borrell warned on Monday that Russia's blockade of Ukrainian ports threatens supplies to countless thousands vulnerable to starvation.