Britain's Foreign Secretary Boris Johnson returns from a morning run on the third day of the Conservative Party Conference in Manchester, Britain, October 3, 2017. REUTERS/Hannah McKay

STRASBOURG (Reuters) - Theresa May should sack Boris Johnson if she wants progress in the Brexit talks, a leading lawmaker in the European Parliament and an ally of German Chancellor Angela Merkel said on Tuesday.

Manfred Weber, a German who leads the centre-right bloc, said during a debate in Strasbourg on the negotiations on Britain’s departure that conflicting statements from the British prime minister’s government, including from Foreign Secretary Johnson, were holding up the process of reaching a deal.

“Please sack Johnson,” demanded Weber, whose conservative group is the biggest in a legislature that must approve any deal which EU negotiators strike with Britain before March 2019.

“The key question is who shall I call in London? Theresa May, Boris Johnson, or even David Davis?,” Weber said, referring also to the minister handling the Brexit talks with Brussels.

On the day when Johnson, a flamboyant and outspoken figure who dominated the hardline campaign to leave the EU, is set to make a keynote speech to the Conservative party conference, Weber said his talk of “red lines” on Brexit showed that the British government was “trapped by their own party quarrels”.

He called on May, who campaigned to stay in the Union and was weakened in a botched snap election in June, to impose herself in the interests of reaching a deal on an orderly exit:

“Theresa May, please don’t put your party first,” Weber said. “Put please Britain first, put the citizens first.

“Please no more speeches. Show leadership on content. And the best probably would be, please sack Johnson.”