The Prime Minister is set to call on EU leaders to introduce "a robust sanctions regime" to deter cyber attacks.
Following the adoption of a new sanctions regime on chemical weapons at the Foreign Affairs Council in Luxembourg, which was tabled by the UK and France in the wake of the Syria and Salisbury attacks, Theresa May will make the case for similar measures to be introduced for cyber attacks.
During a session on internal security at the European Council on Thursday, the prime minister will welcome the decision on chemical weapons as important progress – but will make the case for going further.
"Individual efforts to protect ourselves, and to call out irresponsible behaviour, are not enough," she is expected to say.
"Malign cyber activity causes harm to our economies, and undermines our democracies. As well as protecting ourselves against attack, we must impose proportionate consequences on those who would do us harm.
"We should accelerate work on EU restrictive measures to respond to and deter cyber attacks, including a robust sanctions regime.
"I believe that we have an opportunity to show our collective political leadership. We have demonstrated significant steps forward against other challenging threats."
Mrs May – who is in Brussels for more crunch Brexit meetings – will add that "malicious cyber activities" should be considered "no different" to other threats, and that EU leaders should "impose costs on all those who seek to attack us, regardless of the means they use to do so".
She will say cyber attacks have "real life consequences for the security and prosperity of our nations", and that those behind them must "face the real consequences of their actions".
She will add: "The UK stands ready to share its experience of work on cyber attacks to support the development of an effective regime."
During her speech, Mrs May will also make specific reference to the attempted cyber attack on the Organisation for the Prohibition of Chemical Weapons earlier this year.
She will say that it "is a stark example of the very real threats that we face", but that 'it is also a clear example of where these attacks can be prevented".
More from Politics
She will also commend Dutch Prime Minister Mark Rutte for his nation's efforts and echo his calls for more to be done, "so that not only do we prevent further attacks in the future, but that our demonstrated collective resolve shows that any future attempt will be in vain".
Finally, she will welcome the European Commission's recently published Code of Practice on disinformation, noting that it is the first time online platforms, advertisers and governments have come together to combat it spreading.