Ukraine’s President Volodymyr Zelenskyy has arrived in the UK for “substantive negotiations” with Rishi Sunak, as the UK is set to confirm further military aid for Kyiv.

The Ukrainian president will meet Mr Sunak at Chequers, the prime minister’s country retreat.

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The government said Mr Sunak will confirm today the further provision of hundreds of air defence missiles and further unmanned aerial systems including hundreds of new long-range attack drones with a range of over 200km.

Mr Sunak said it was a “crucial moment” in Ukraine’s resistance against Russia’s invasion, adding: “We must not let them down.”

It comes as Mr Zelenskyy embarks on a multi-stop European tour for more support from allies, as Kyiv prepares for its counteroffensive against Russian forces.

Mr Zelenskyy tweeted ahead of his arrival, describing the UK as a “leader” when it comes to Ukraine expanding its capabilities on the ground and in the air.

The UK government’s announcement of further military aid follows last week’s confirmation that it has donated long-range precision missiles to Ukraine’s military.

The government said the further provisions which will be confirmed later today will be delivered in the coming months.

On Saturday, the German government promised Kyiv its biggest military support package so far, with further arms deliveries worth €2.7bn (£2.35bn).

France also pledged further military aid, as French president Emmanuel Macron and Mr Zelenskyy met in a surprise summit in Paris on Sunday.

Mr Macron’s office said France will supply dozens of light tanks and armoured vehicles “in the weeks ahead”, without giving specific numbers.

Fierce fighting in Ukraine’s eastern city of Bakhmut, which has inflicted heavy losses on both sides, continues.

Neither Kyiv nor Moscow’s forces have been able to take full control of the city despite months of fighting, as analysis suggesting the battle for the city is not about seizing ground but maximising enemy casualties.

Mr Zelenskyy has said his troops would not attack Russian territory as part of their counteroffensive.