Liz Truss is set to meet European leaders next week at a new community initiative proposed by France’s Emmanuel Macron.
The Prime Minister will jet to Prague for the inaugural gathering of the “European political community”, marking her second overseas visit since taking the reins of Downing Street.
Ms Truss decided to attend after energy and migrants, the Prime Minister’s top priorities, were listed at the top of the event’s agenda.
Downing Street sources say that it was also vital Ukraine would be attending in some capacity.
However, British diplomats have warned the summit’s EU conveners that it cannot cut across NATO and G7, and that the voices of non-EU members should be emphasised.
The decision to attend comes after the Élysée was left disgruntled by Ms Truss refusing to acknowledge the French president as an ally, after claiming questions remain whether he is a friend or foe.
When asked the question during the Conservative leadership campaign, the now Prime Minister said the “jury’s out” over whether Mr Macron was a trusted ally.
Earlier this year, announcing the scheme, the French president said it brings together non-EU members - including countries such as those of the Balkans, Moldova, Georgia and Ukraine - with the bloc’s 27 states.
He also insisted the community should be open to those who had left the EU, in an attempt to entice Britain to join the gathering.
Turkey, Switzerland and Norway are also expected to join the summit.
According to European sources, Ms Truss agreed to attend on the basis that migration is properly addressed, the EU plays a less significant role in the future and the next host is not a member of the bloc.
The conflict in Ukraine and the energy crisis fuelled by Vladimir Putin's invasion will take centre stage at the meeting in the Czech capital.
Eastern European and Baltics diplomats are buoyed by the news, given their belief that Britain provides better security guarantees in the face of Russian aggression than the majority of EU members, including France and Germany.
As part of the agreement to join the community meeting, Ms Truss reportedly insisted that Britain should host the next meeting.
British diplomats also proposed changing its name to the “European political forum”.