Turkey's foreign minister said on Wednesday a United Nations plan to ease a global food crisis by restarting Ukrainian grain exports along a sea corridor was "reasonable", and required more talks with Moscow and Kyiv to ensure ships' safety, reported Reuters.

Speaking alongside Russian Foreign Minister Sergei Lavrov, Turkey's Mevlut Cavusoglu said their meeting in Ankara was fruitful, adding Turkey's latest contacts and Ukrainian President Volodymyr Zelenskiy's recent statements showed there may be a basis for a return to talks.

But Ukraine's ambassador to Turkey accused Russia of putting forward unrealistic proposals, such as checking vessels.

Lavrov said the onus was on Ukraine to solve the grain shipments problem by clearing mines from its Black Sea ports and that Russia needed to take no action because it had already made the necessary commitments.

"We state daily that we're ready to guarantee the safety of vessels leaving Ukrainian ports and heading for (Turkish waters), we're ready to do that in cooperation with our Turkish colleagues," he said after the talks with Cavusoglu.

Ukraine's foreign ministry, however, dismissed as "empty words" Lavrov's assurances that Moscow will not use the situation to its advantage if Kyiv allows grain shipments to leave safely via the Black Sea.

Ukraine has said it needs "effective security guarantees" before it can start shipments, voicing concerns that Moscow could use the potential corridor to move on its southern port of Odesa.

Russia's 24 February invasion of Ukraine halted Kyiv's Black Sea grain exports, threatening a global food crisis. The United Nations appealed to the two sides, as well as maritime neighbour and NATO member Turkey, to agree a corridor.

Moscow denies responsibility for the international food crisis, blaming Western sanctions.

Any deal could involve a Turkish naval escort for tankers leaving Odesa and other Ukrainian ports - which are currently blockaded by Russia's navy - and onward to Turkey's straits and global markets.

Cavusoglu said he believed the world should work together to open a safe passage for Ukraine's agricultural exports and that Turkey viewed Russian demands to lift restrictions on its farm exports as "very legitimate".

"Various ideas have been put out for the export of Ukrainian grains to the market and most recently is the UN plan (including) a mechanism that can be created between the UN, Ukraine, Russia and Turkey," Cavusoglu said.

"We see it as reasonable," he added. "Of course both Ukraine and Russia must accept it."

Lavrov said the main problem was that Ukraine had "categorically refused" to resolve the mined ports' problem.

Turkey, which has good relations with both Kyiv and Moscow, has previously said it is ready to take on a role within an "observation mechanism" based in Istanbul if a deal is reached.

Turkey has the second biggest army in NATO and a substantial navy, but the head of the Ukrainian grain traders union said on Wednesday Ankara was not powerful enough to act as a guarantor.