As one of the brokers of the grain deal, Turkey has stepped up diplomacy with the two warring countries in a bid to save it as Russia warned that continuing to enforce the agreement without its participation would be "dangerous".

At least 10 ships including the Ikaria Angel -- chartered by the World Food Programme and loaded with 30,000 tonnes of wheat destined for an emergency response in the Horn of Africa -- left Ukrainian ports on Monday, according to a website that tracks marine traffic.

"Civilian cargo ships can never be a military target or held hostage. The food must flow," Amir M. Abdulla, the UN Coordinator for the Black Sea Grain Initiative, tweeted on Monday.

In all, 12 ships were due to leave Ukrainian ports on Monday and four more were due to head to the country, according to the Joint Coordination Center (JCC) that has been overseeing the agreement brokered by Turkey and the UN.

-'Continue our efforts'-

The marine traffic came two days after Russia notified the UN and Turkey that it was suspending its participation in the grain agreement, after Moscow accused Ukraine of a "massive" drone attack on its Black Sea Fleet in Crimea.

Ukraine has labelled the Russian charges as a "false pretext".

Moscow also withdrew from ship inspections, which were mandatory under the deal.

Grain prices were up on Monday morning after the Russian decision.

Turkish President Recep Tayyip Erdogan vowed to pursue efforts to keep the agreement in force despite Russia's moves.

"Although Russia acts hesitantly... we will resolutely continue our efforts to serve humanity," Erdogan said in a televised address.

Monday's shipping schedule was agreed by the Ukrainian, Turkish and UN delegations, with Russia informed of the movements, the JCC said in a statement late on Sunday.

A source familiar with the matter said: "As a signatory to the agreement, they have been requested to take the necessary measures to ensure the safety of the vessels."

- 'Dangerous'-

The Kremlin said it would be "dangerous" to enforce the agreement without its involvement.

"In conditions where Russia talks about the impossibility of guaranteeing the safety of navigation in these areas, such a deal is hardly feasible. And it takes on a different character, much more risky, dangerous," Kremlin spokesman Dmitry Peskov told journalists.

Turkey's defence minister Hulusi Akar said talks were under way with the relevant parties for the agreement to remain in place.

Akar said he spoke with Ukrainian authorities and would contact his Russian counterpart, Sergei Shoigu, on Monday evening.

"This (agreement) should continue. Suspending this initiative will not benefit Russia, Ukraine or anyone else," he said, urging the parties "to review their decisions."

Ukraine, one of the world's largest grain exporters, was forced to halt almost all deliveries following Russia's invasion in late February.

The July deal to unlock its grain exports is critical to easing the global food crisis caused by the conflict.

The agreement, which established a safety corridor through which vessels could travel to Istanbul for inspections, had already allowed more than 9.5 million tonnes of Ukrainian grain to be exported and was due to be renewed on November 19.

A separate deal signed with Russia allowed the export of Russian food and fertilisers, despite Western sanctions imposed on Moscow. But it was never implemented, to the dismay of Moscow, which has complained about the issue for weeks.

On Thursday, a few days before Russia's suspending its participation in the grain deal, its ambassador to the UN Vassily Nebenzia told reporters that Russian exports must be allowed to go through before Moscow would commit to a deal extension.