The piece appeared on a building on the A20 in Kent overnight.
Pictures of the mural, near Dover's ferry terminal, have been posted on Banksy's Instagram account, and a representative confirmed it was his.
The mysterious artist is known for his political pieces. His latest comes as the UK heads towards a general election and Britain prepares to leave the EU.
BBC - iWonder - How did Banksy become the world's most famous vandal?
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A mural of a workman removing a star from the EU flag has been confirmed as the work of graffiti artist Banksy.