Britain's Foreign Secretary Boris Johnson attends a news conference with French Foreign Minister Jean-Yves Le Drian, German counterpart Sigmar Gabriel and European Union's foreign policy chief Federica Mogherini after meeting Iran's Foreign Minister Mohammad Javad Zarif (unseen) in Brussels, Belgium January 11, 2018. REUTERS/Francois Lenoir

LONDON (Reuters) - Foreign minister Boris Johnson has told friends he is worried that Britain will accept a Brexit deal that leaves it subordinate to Brussels, making the 2016 EU referendum a “total waste of time”, the Sun newspaper reported on Monday.

Johnson, one of the most senior pro-Brexit government ministers, is seen as a potential successor to Prime Minister Theresa May. He was one of the most prominent supporters of leaving the European Union during a divisive referendum campaign.

“I’d rather us stay in than leave like that,” the newspaper quoted Johnson as telling friends in an unsourced report.

A spokesman for Johnson declined to comment on the report.

May, who voted ‘Remain’ in 2016 but has committed to guiding Britain out of the bloc, is seeking a two year transition period after a March 2019 exit, during which Brussels rules would still apply. She wants a long term divorce deal that would allow “frictionless” trade with the bloc.

That plan has led to criticism from some Brexit advocates that Britain could end up leaving in name only, and would remain subject to rules set by the EU.

Last week another senior Brexit campaigner, Nigel Farage, said he was warming to the idea of a second referendum as a way to end attempts by some senior politicians, including former Prime Minister Tony Blair, to stop Britain from leaving.