Ukraine on Monday condemned what it called "provocative" Russian actions and called for decisive countermeasures by the international community, a day after Moscow said one of its warships fired warning shots at a cargo vessel in the Black Sea.

Moscow said on Sunday that its Vasily Bykov patrol ship fired automatic weapons on the Palau-flagged Sukru Okan vessel after the ship's captain failed to respond to a request to halt for an inspection.

Russia has said it would treat any ships approaching Ukrainian ports as potential military vessels after it left a U.N.-brokered deal last month that allowed the safe passage through the Black Sea of Ukrainian grain.

"The Ministry of Foreign Affairs of Ukraine strongly condemns the provocative actions carried out by the Russian Federation on August 13 in the Black Sea in relation to the Turkish dry cargo vessel 'Sukru Okan,' which was en route to the port of Izmail," the ministry said in a statement.

Kyiv said the incident was a gross violation of international law and "exemplified Russia's deliberate policy of endangering the freedom of navigation and safety of commercial shipping in the Black Sea."

"We call on the international community to take decisive action to prevent Russian Federation's actions that impede the peaceful passage of vessels through the Black Sea," the ministry said, without specifying what action it had in mind.

In a statement late on Sunday, a Ukrainian deputy prime minister called on the International Maritime Organisation to "react firmly" to the incident and suggested ships should adjust their course to minimize the risk of Russian interference.

"In order to avoid provocations, we recommend that masters of vessels sailing to/from Ukrainian seaports sail as close as possible to the coast of the northwestern part of the Black Sea, through the territorial waters of Türkiye, Romania and Bulgaria," Oleksandr Kubrakov tweeted.

The incident cast a pall over plans for a "humanitarian corridor" in the Black Sea to release cargo ships trapped in Ukraine's ports since the outbreak of war.

Ukraine has started registering ships willing to use the corridor, which it announced earlier this week, a local news agency said on Saturday. Shipping and insurance sources have expressed concerns about safety.