European Council President Donald Tusk poses with European Union's chief Brexit negotiator Michel Barnier ahead of meeting in Brussels, Belgium September 13, 2018. Francisco Seco/Pool via REUTERS

BRUSSELS (Reuters) - The European Union’s chief Brexit negotiator Michel Barnier said on Friday that key differences remained between the EU and Britain over the future of the Irish border and the EU’s system of protecting food names.

Barnier tweeted that he had a “useful dialogue” with his British counterpart Dominic Raab on Friday morning about progress their teams had made toward a withdrawal agreement.

“But substantive differences remain on the Protocol for IE/NI, governance and GIs (geographical indications),” Barnier said on Twitter. “We are also continuing our discussions to find common ground on the future relationship.”

The European Union wants a deal over Britain’s exit from the bloc to guarantee there will be no hard border between Northern Ireland and Ireland.

It also wants Britain to uphold the EU’s system of geographical indications, which stipulate for example that the term champagne can only be used for sparkling wine from a specific region of France or that feta is only from Greece.