Russian President Vladimir Putin is set to meet his Turkish counterpart Recep Tayyip Erdoğan in Iran next week as international efforts intensify to unblock Black Sea shipping routes and allow the resumption of Ukrainian grain shipments.

Kremlin spokesman Dmitry Peskov confirmed reports the meeting will take place when Putin is in Tehran next Tuesday. “We informed about the upcoming high-level contacts between Putin and Erdoğan, this meeting will also be held there,” he said.

Erdoğan spoke by phone Monday with Putin and Ukraine’s President Volodymyr Zelenskyy, seeking an agreement to relax Russia’s blockade of Ukrainian seaports and allow grain exports to resume.

“President Erdoğan noted that it was time for the United Nations to take action for the plan regarding the formation of secure corridors via the Black Sea for the grain export,” a Turkish readout from his call with Russia’s president said.

Ukraine was a major agricultural exporter and the blockade of its ports since Russia’s invasion in February has left million of tons of grain stuck in silos, raising fears of hunger in importing countries such Egypt, Tunisia and Algeria.

The announcement of face-to-face talks between Putin and Erdoğan has raised hopes of progress toward a deal.

However, Zelenskyy is anxious to avoid an agreement that would see Russia exporting cereals it seized from captured Ukrainian territory. Last week, Ukraine summoned Turkey’s ambassador complaining Ankara had released a Russian ship with a cargo of “stolen” Ukrainian grain.

Meanwhile, the United States expressed concern Monday about Russian military ties with Iran ahead of Putin’s visit. National Security Adviser Jake Sullivan told reporters Russia is seeking to acquire “several hundred” drones from Teheran.

The Kremlin said Putin, Erdoğan and Iranian President Ebrahim Raisi would discuss the situation in Syria where all three have been involved in the conflict. Putin’s visit will follow a trip to the Middle East this week by U.S. President Joe Biden, where he expected to discuss concerns over Iran’s military and nuclear programs in Israel and Saudi Arabia.

The Iran visit will be Putin’s second foreign trip since he ordered the invasion of Ukraine. He visited Central Asia in June.

Mohammadreza Pour-Ebrahim, head of the Iranian parliament’s economy commission, said the visit would focus on “development of economic cooperation between Iran and Russia,” Iranian news agency Mehr reported. Raisi visited Russia in January, Politico reports.