The funding package for the coming year is pound200 million higher than the pound2.3 billion pledged per year in both 2022 and 2023.

It will ensure the "largest ever commitment of drones", Sunak's office said in a statement.

The UK prime minister said the aid was designed "to send a strong signal of support to the Ukrainian people".

Russian President Vladimir Putin "needs to recognise we're not going anywhere", he added.

"I'm here with one clear message: the United Kingdom stands with Ukraine," he said after touring damaged buildings in the Ukrainian capital.

Sunak met emergency service workers responding to the aftermath of Russian air strikes and praised Ukrainians' "great courage".

The British leader was set to sign a "historic" security cooperation pact with Ukrainian President Volodymyr Zelensky while in Kyiv, his office said.

The "totemic agreement" should be the first step towards an "unshakeable hundred-year partnership", it added.

- 'Seriousness of the situation' -

At least pound200 million of the latest aid package is to be spent on "a major push to rapidly procure and produce thousands of military drones for Ukraine, including surveillance, long-range strike and sea drones".

Sunak said the aid currently in place was due to run through to the "early part of this year".

"So we're acting in advance of that expiring with a new commitment of two and a half billion pounds -- more than we've provided in previous years," he told reporters.

"That represents the seriousness of the situation here and our determination to stand with Ukraine," he added.

The latest commitment takes the UK's overall support for Ukraine's war efforts to almost pound12 billion.

The equipment already supplied to Kyiv includes Storm Shadow cruise missiles and a squadron of Challenger 2 tanks.

British Foreign Secretary David Cameron vowed, during a surprise visit to Kyiv in November, to maintain military support for Ukraine.

Zelensky said at the time that the flow of vital artillery ammunition from Western allies had dropped since the start of the war between Israel and Hamas in October.

"We will continue to give you the moral support, diplomatic support, the economic support, but above all, the military support, that you need not just this year, and next year, but for however long it takes," Cameron said during a meeting with Zelensky in November.

A top Ukrainian commander recently described the war as a stalemate, with no clear sign of a breakthrough on the front lines.