John Whittingdale, the former culture secretary and Leave supporter, has urged Prime Minister Theresa May to trigger Article 50 within weeks.
Invoking Article 50 is the official signal for leaving Europe and will trigger a two year period of negotiations with Brussels.
“Article 50 is the beginning of the process rather than the end. I don’t see what holds us back. We do need to get the formal process under way. I don’t say that it has to happen tomorrow but I would like it to happen pretty soon, and by that I mean weeks, not months," Whittingdale told the Telegraph in his first interview since he was ousted from the Cabinet in May's shake up.
It follows call by the president of of the European Council Donald Tusk who earlier this week urged May to start the process "as soon as possible" in a meeting at Downing Street.
Article 50 won't be triggered this year according to government lawyers and others have urged the PM to push back firing the starting gun on the process to take into account political events in Europe scheduled next year. France and Germany are due to head to the polls over the summer and early autumn.
Meanwhile, a group of pro-Leave campaigners have formed a cross-party "Brexit means Brexit" pressure group which also has backing from foreign secretary Boris Johnson.