“In order to force the ship to stop, warning shots were fired with light automatic weapons from a Russian warship,” the ministry said on Telegram.

According to Moscow, the captain of the Palau-flagged vessel, the Sukru Okan, had not responded to an order to stop for “an inspection concerning the transport of prohibited goods”.

A helicopter with Russian military personnel on board then took off to inspect the ship, which was allowed to continue its journey to the Ukrainian port, according to the same source.

The news of the encounter comes just as Ukraine begins registering ships willing to use a safe “humanitarian corridor” it is trying to establish in the Black Sea, with a view to allowing trapped cargo ships to finally set sail.

It is not yet clear if Russia will acknowledge or respect the plan.

Bottleneck

The river port of Izmail, in the Odessa region, has become one of the main exit routes for Ukrainian agricultural products since Moscow terminated the agreement on grain exports.

In mid-July, Moscow terminated the agreement that had allowed Ukrainian grain to leave the country’s southern ports since last summer, despite the blockade put in place by Russia.

A few days later, on 19 July, Moscow warned that any ship travelling to or from Ukrainian ports would be considered a potential target. Kiev reacted the next day by saying the same would apply to Russian ships.

Since then, the number of attacks in the Black Sea has increased on both sides and the Russian army has struck Odessa, a major port in southern Ukraine, as well as the river ports of Izmaïl and Reni on several occasions, attacks denounced by Kiev as a means of hindering its exports.

Ukraine hit the Russian port of Novorossiysk and several Russian ships in the Black Sea, including an oil tanker.