Sunak will arrive in Latvia on Monday for the meeting to discuss ongoing efforts to counter Russian aggression in the Nordic and Baltic region with fellow members of the Joint Expeditionary Force (JEF), AFP said.

Sunak will call on the leaders to maintain or exceed 2022 levels of support for Ukraine in 2023, a statement issued by the prime minister's office said.

He will also announce that the UK will supply "hundreds of thousands of rounds of artillery ammunition next year under a £250 million ($304 million) contract that will ensure a constant flow of critical artillery ammunition to Ukraine throughout 2023", the statement said.

The UK had led the way in "providing defensive aid to Ukraine including sending Multiple Launch Rocket Systems and recently 125 anti-aircraft guns", it said.

"We have also provided more than 100,000 rounds of ammunition since February, with the deliveries directly linked to successful operations to retake territory in Ukraine," it added.

Sunak last month visited Kyiv to offer further support to Ukraine in its fight against Russian forces following the February invasion.

"The UK and our European allies have been in lockstep in our response to the invasion of Ukraine, and we remain steadfast in our ambition for peace in Europe once again," Sunak said in the statement.

"But to achieve peace, we must deter aggression and our deployments across the region together are vital in ensuring we are able to respond to the gravest of threats," he added.

The JEF meeting, which brings together the leaders of Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, the Netherlands, Norway, Sweden and the United Kingdom, will also be addressed by President Volodymyr Zelensky.