Boris Johnson arrives at BBC studios to take part in a TV debate with candidates campaigning to replace British Prime Minister Theresa May, in London, Britain June 18, 2019. REUTERS/Peter Nicholls

LONDON (Reuters) - Boris Johnson, the leading candidate to be Britain’s next prime minister, said on Tuesday the issue of what to do with the Irish border after Brexit could be solved during the implementation period with the European Union.

“You can solve the questions of how do you keep goods flowing freely across that border whilst the UK comes out of the EU as a whole. You can solve that issue during the implementation period whilst we negotiate the free-trade deal,” Johnson said in a televised debate with the other four remaining candidates. “That is the way forward.”

Managing the sensitive border between the British province of Northern Ireland and EU member Ireland and designing an emergency backstop solution to prevent the return of extensive controls after Brexit has proven the most contentious element of divorce negotiations between London and the bloc.