The EU has a large number of international agreements which underpin relations with more than 100 so-called third countries, covering issues such as trade, nuclear cooperation and aviation.
In a technical note, the Department for Exiting the EU says these countries "will have an interest in their continued proper functioning" in the transition period after Brexit in March 2019.
"This would be achieved by agreement of the parties to interpret relevant terms in these international agreements, such as 'European Union' or 'EU Member State', to include the UK," it said.
Britain is hoping for a two-year transition period to smooth its withdrawal from the bloc, during which its relationship with Brussels will remain largely the same.
The technical note, published on Thursday, suggests the approach outlined would be the "simplest way" of ensuring the continued application of the agreements, and avoiding the "risk of disruption" of the agreements.
But the move drew some mockery as British Prime Minister Theresa May has repeatedly said that "Brexit means Brexit".
"To coin a phrase, they are going to tell the world that Brexit does not mean Brexit," an unnamed EU official told the Financial Times newspaper.
Britain and the EU began formal talks on the transition on Tuesday but the week ended with the bloc's chief negotiator, Michel Barnier, warning of "substantial" disagreements.