Despite leaving the trade bloc two years ago, the UK has been invited to attend the extraordinary meeting to ensure there is a united approach across the West on how to deal with Russia.
Ms Truss confirmed her attendance at a press conference in Lithuania.
The US, Canada, and Ukraine have also been invited to the EU meeting.
The Foreign Secretary said “we need to go further” on introducing sanctions against Moscow as she called for Russia to be expelled from the Swift finance system completely.
Ms Truss said: “I will be raising these issues at the G7 tomorrow and also at the European Union foreign affairs council alongside the United States, Canada, and Ukraine, who have also been invited in these extraordinary circumstances.”
More to follow…
