Britain is ready for a new and improved relationship with Russia in the wake of the United Kingdom government accusing the Kremlin of masterminding an attempted assassination on British soil and alleging Moscow orchestrated online meddling in the UK's democratic process, and conducted cyberattacks, claims Russia has strenuously denied.

UK Prime Minister Theresa May was set to say on Monday evening that Britain is "open to a different relationship" following a year of deteriorating ties, as long as Moscow changes its tack and stops "attacks" that undermine international treaties and security.

Reuters said May would use her annual speech at the Lord Mayor's Banquet in the heart of London's financial district to extend an olive branch, saying the time had come to move on from the status quo that saw the UK expel the largest-ever contingent of Russian intelligence officers in retaliation for the alleged attempted assassination in the small UK city of Salisbury in March of a Russian former double-agent, a claim Moscow denies.

"We will continue to show our willingness to act, as a community of nations, to stand up for the rules around the world," excerpts of her speech indicated she was set to say.

But Reuters said she would go on to say: "This is not the relationship with Russia that we want ... We remain open to a different relationship, one where Russia desists from these attacks that undermine international treaties and international security … And we hope that the Russian state chooses to take this path. If it does, we will respond in kind."

Observers said the tone of the speech would highlight May's insistence that Britain's decision to leave the European Union, which is scheduled to take place at the end of March, does not mean the nation wants to isolate itself, or step down from the global stage.

The Guardian newspaper reported that May would praise the coordinated response from nations in response to the UK's allegations against Russia, and herald the work of the Dutch authorities in thwarting an apparent attempt to hack into the computers of the international chemical weapons watchdog in The Hague.