Kyiv announced Wednesday a cargo vessel had exited its southern port of Odesa along a new maritime corridor, despite an earlier warning from Russia it could target vessels using Ukrainian ports. 

The announcement, which raises the spectre of an intervention by Russian warships, came hours after Ukraine said it had liberated a village as part of a grinding push to wrest Moscow's forces along the southern front.

Russia issued its maritime threat after scuppering a key deal last month -- brokered by the UN and Turkey -- that guaranteed safe passage for grain exports from three Ukrainian ports.

"The first vessel is moving along the temporary corridors established for civilian vessels to and from Black Sea ports," Ukraine's Infrastructure Minister Oleksandr Kubrakov said in a statement. 

He named the vessel as the Hong Kong-flagged Joseph Schulte, and said it had left the port of Odesa -- one of three transit hubs that participated in the now-scrapped grain deal.

Since Russia's exit, it has stepped up attacks on Ukraine's Black Sea port infrastructure and facilities Kyiv uses to export grain through the Danube river.

- Drones batter Odesa port -

In the latest attack, the governor of the Odesa region said Wednesday that Russian attack drones had damaged grain facilities at a river port near its western border.

The airforce meanwhile said it had downed 13 Russian drones over Odesa and the neighbouring Mykolaiv region. 

The incident sparked an outcry in neighbouring Romania, which is now a key hub for Ukrainian grain exports abroad since the collapse of the exports deal. 

"I strongly condemn the continued (Russian) attacks on innocent people, civilian infrastructure, including grain silos in the ports of Reni and Izmail," Foreign Minister Luminita Odobescu posted on social media. 

The possibility of a Russian attack on cargo ships on the Black Sea increased after last week, when Moscow said it fired warning shots from a Russian warship at a cargo vessel heading towards Izmail. 

The cargo ship left Odesa hours after Ukraine's military announced the capture of Urozhaine, a small hamlet in the industrial Donetsk region that the Kremlin claims is part of Russia.

"Our defenders are entrenched at the outskirts. The offensive continues," Deputy Defence Minister Ganna Malyar announced in a statement on social media.

Kyiv launched its long anticipated counteroffensive in June, but has acknowledged tough battles as it struggles to break through heavily fortified Russian positions.

- Ukraine pushes on southern front -

Malyar's announcement comes one day after Russian defence minister Sergei Shoigu said that Ukraine's military resources were "almost exhausted", despite receiving arms deliveries from Western allies. 

There was no immediate response to the Ukrainian claim from Moscow, which has repeatedly downplayed Kyiv's offensive capabilities.

The Donetsk region -- which has faced the brunt of fighting in recent months -- is one of four Ukrainian regions that the Kremlin claimed to have annexed last year, months after invading in February.

Its governor Pavlo Kyrylenko announced on Wednesday morning that four people had been killed and another seven injured in the region by Russian forces over the past 24 hours.

Urozhaine, with an estimated pre-war population of around 1,000 people, is among a cluster of villages that Ukrainian forces have been attempting to wrest over recent weeks.

Further east in the region, Ukrainian forces have also been fighting to push back Russian forces from the north and south of the war-battered town of Bakhmut.

The town of some 70,000 people was captured in May after a months-long and brutal battle but immediately Ukrainian forces began clawing back ground around its flanks.

And Russia announced that its air defence systems had downed several drones overnight near the capital, in the latest of a string of aerial attacks that have targeted Russia's urban centres.

The defence ministry said three drones were shot down in the Kaluga region south of the capital, while regional officials said there was no damage or casualties. 

The air attack is at least the fifth this month over the Kaluga region that Russia says it has thwarted. 

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