ISTANBUL, Aug 17 (AFP) - A civilian cargo vessel sailing from Ukraine reached Turkish waters on Thursday (Aug 17) in defiance of a Moscow blockade that saw another ship come under attack from Russian military personnel.

The Hong Kong-flagged Joseph Schulte left the port of Odesa on Wednesday - the first vessel to directly challenge Russia's new bid to seal Ukraine's access to the Black Sea.

Marine traffic sites showed it entering Turkish territory after moving along a western route that avoided international waters in favour of those controlled by NATO members Romania and Bulgaria.

A German company that co-owns the container vessel said it would "probably" reach its destination in Istanbul later Thursday.

Ukrainian President Volodymyr Zelenskyy said the ship was using a "new humanitarian corridor" that Kyiv established after Russia last month scuppered a landmark agreement allowing Ukraine to export grain and foodstuffs across the Black Sea.

The Joseph Schulte's mission came days after the Russian navy fired warning shots and boarded a small Turkish-crewed cargo ship that was travelling to the Ukrainian port of Izmail.

Russia has stepped up attacks on Ukrainian Black Sea and Danube River port infrastructure since pulling out of the UN and Türkiye-mediated grain deal.

Ukraine's Infrastructure Minister Oleksandr Kubrakov said the new sea route "will be primarily used to evacuate ships that were in ports at the time of the full-scale invasion" in February of last year.

But Ukraine's decision to confront Russia over sea access comes with world attention focusing on ways to secure grain export routes in time for this autumn's harvest.

Ukraine and Russia are major exporters of grain and seed oil.