Zelenskiy said Kyiv was working to strengthen its position in the Black Sea so that it can continue grain exports, which are vital to ensuring budget revenues following a surge in defence spending following Russia's invasion last year.

"We are working with partners to protect properly these corridors, and strengthen our positions in the Black Sea, and it also applies to the protection of Odesa's skies and in the region as a whole ...," he told a joint press conference alongside Rutte.

Ukraine's government outlined details of Russian attacks on infrastructure and the results of the alternative "humanitarian" corridor organised by Ukraine since Russia abandoned a U.N.-backed accord on safe Black Sea grain shipments in July.

It said Russia has destroyed almost 300,000 metric tons of grain since July in attacks on Ukraine's port facilities and on ships. Russia's Defence Ministry did not immediately respond to a request for comment on Ukraine's allegations.

Deputy Prime Minister Oleksandr Kubrakov said that since that deal ran out, Russian forces had hit six civilian ships and 150 port and grain facilities during 17 attacks, destroying crops headed for export.

Kubrakov said 21 grain-loaded vessels had already used the new grain corridor.

The Odesa region has came under frequent Russian missile and drone attacks, and Zelenskiy and Rutte visited a damaged port.

Ukraine has sought safe shipping routes as air strikes inflicted damage on its port and grain export infrastructure near the Black sea and on the Danube River.

Rutte said the Netherlands would provide more Patriot air defence missiles to help Ukraine defend itself in the winter. The Netherlands would also help Ukraine acquire patrol boats, he said, to help keep the grain export route safe.

The Netherlands has provided Ukraine with financial aid and weapons during the war, and has led efforts to help train Ukrainian pilots on F-16 fighter jets.

Ukraine's humanitarian corridor was initially announced to release ships that do not carry grain, were not covered by the grain deal and had been trapped in port for more than a year, but vessels seeking to load grain have also used the corridor.

Zelenskiy also said Ukraine was nearing an agreement with some partners on insurance for ships using the corridor, but gave no details.

(Reporting by Iryna Nazarchuk; Writing by Olena Harmash; Editing by Timothy Heritage, Ron Popeski and Alison Williams)