LONDON, Dec 4 (Reuters) - Brexit trade talks are in the difficult phase and a deal can only be struck if the European Union accepts that Britain is a sovereign nation, Business Secretary Alok Sharma said.

"We are at a critical phase," Sharma told Sky TV. "It is fair to say that we are in a difficult phase, there are some tricky issues still to be resolved."

"Right from the start of this process, we've always said that a deal can only be done if the EU recognises that the UK is a sovereign independent nation," Sharma said. "It is on the basis of that a deal will be done." (Reporting by Guy Faulconbridge and Kate Holton; editing by Michael Holden)