Six people have been killed in Ukraine following an overnight Russian attacks on the Black Sea port of Odesa and the eastern city of Sumy, according to local officials.

Governor of Odesa region Oleh Kiper said the "massive" drone and missile strike marked the fifth day in which Russia has attacked the region.

Across the country, three people were killed and 17 injured in a "guided aerial bomb" attack on Sumy, the city's acting mayor, Artom Kobzar, said.

Meanwhile, Ukraine's military said its drones hit 20 Russian vessels, including 17 oil tankers, in the Black Sea overnight.

The Russian ministry of defence confirmed it had attacked Odsea, saying it had deliberately targeted port infrastructure, "used for the unloading of petroleum, oil, and lubricants".

Writing on Telegram, Kiper accused Russia of deliberately targeting the civilian population and said residents were killed and injured when a Russian missile struck a multi-storey residential building.

He added that a non-residential building and a gas pipeline were also hit.

In its statement, Russia claimed to have targeted sites involved in the manufacture of military hardware, and the transport of cargo.

Russia's attacks in recent days have targeted Ukraine's deep-water Black Sea ports in the wider Odesa area, which handle much of the country's grain and other cargo and are vital to its wartime economy.

It follows intensive attacks on Russian ships in the Sea of Azov, which sits between Crimea, Ukraine's eastern coastline, and Russia.

The Ukrainian attacks have forced Russia, the world's top grain exporter, to restrict shipping in the Sea of Azov – a route that handles about a quarter of its grain exports, according to news agency Reuters.

As the attacks continue, Ukraine is attempting to navigate a tumultuous political situation which has seen President Volodymyr Zelensky dismissing Prime Minister Yulia Svyrydenko after less than a year in the post.

A motion to accept Svyrydenko's resignation was passed in Ukraine's parliament on Tuesday, despite some lawmakers questioning whether the reason for the change had been explained.

Serhiy Koretskyi, the head of state oil and gas firm Naftogaz, is seen as a likely successor to Svyrydenko, with parliament set to vote on the appointment on Thursday.

On Wednesday morning, European Commission President Ursula von der Leyen arrived in Kyiv to discuss co-operation between European and Ukrainian defence industries.