Ukraine’s military and Russia’s private Wagner Group army reported fresh Russian retreats on the outskirts of Bakhmut, as Kyiv pressed on with its biggest advance for six months ahead of a planned major counteroffensive.

    Dozens of Russian cruise missiles were fired in the Odesa region and the capital, Kyiv, overnight, Ukraine says, while claiming its defence forces shot down 29 out of 30.

    At least one person was killed in Odesa during the raids, according to Ukrainian officials. Moscow said it hit its military targets.

    Rail traffic has been suspended between Simferopol, the capital of the Crimean Peninsula annexed by Russia, after a train carrying grain derailed. Moscow-backed officials have called the incident a deliberate act.

    Ukraine said it had repelled a day of Russian attacks in and around the ruined eastern city of Bakhmut and made gains of a kilometre in some places while buying time for “certain planned actions”.

    The head of the Wagner Group of mercenaries said his forces had advanced up to 400 metres. “We’re pushing Bakhmut all the way to the end,” Yevgeny Prigozhin said in an audio recording on his Telegram channel.

    Ukraine’s forces advanced 500m in the north and in some areas in the south by one kilometre, Deputy Defence Minister Hanna Malyar said on her Telegram channel.

    “The defence of Bakhmut and its outskirts is meeting its military objectives,” she said. “As of now, we control the southwestern part of Bakhmut.”

    She said that Russia had attacked Bakhmut all day having “significantly strengthened” its grouping in Bakhmut by bringing most of its reserves there.

    “All the attacks were repelled by our defenders,” she said.

    Three new ships were authorised to take part in a deal allowing the safe Black Sea export of Ukraine grain, said the United Nations as global wheat prices fell further a day after Russia agreed to extend the pact for 60 more days.

    Russia had threatened to quit the Black Sea Grain Initiative (BSGI) if a list of demands to overcome obstacles to its own grain and fertiliser exports was not met by May 18. The Kremlin said it had extended the agreement because some results from talks had given it “certain hopes”, but more progress needed to be made.

    The BSGI’s Joint Coordination Centre authorised three new vessels to travel to the Ukrainian ports of Odesa and Chornomorsk, said UN deputy spokesperson Farhan Haq.

    “While we welcome this partial resumption of inbound movement activity, we call on the parties to ensure that the authorisation of new vessels is done for all three ports to make use of capacity and meet industry demands,” Haq told reporters.

    The Pentagon overvalued US equipment it sent to Ukraine by around $3bn, a Senate aide and a defence official has said, an error that opens up the possibility of more weapons being sent to Kyiv for its defence against Russian forces.

    The error was the result of assigning a higher-than-warranted value on weaponry that was taken from US stocks and then shipped to Ukraine, two senior defence officials said.

    “We’ve discovered inconsistencies in how we value the equipment that we’ve given” to Ukraine one of the senior defense officials told the Reuters news agency. The officials and the Senate aide spoke on the condition of anonymity. Congress is being notified of the accounting adjustment on Thursday, the sources said.

    The defence official said it is possible the amount of overvalued weaponry could grow as the Pentagon examines the situation more thoroughly, increasing the $3bn.

    Ukrainian Deputy Defence Minister Hanna Maliar says in a Telegram post that Kyiv’s forces had repelled a daylong attack by Russia in Bakhmut.

    “The enemy gathered most of its reserves to Bakhmut and significantly strengthened the group,” she said. “Today, the enemy attacked Bakhmut for the entire day. All attacks were repelled.”