LONDON (BLOOMBERG) - Brexit Secretary Dominic Raab said Britain must not agree to extend the Brexit transition period unless the European Union drops its demand for a fallback to protect Northern Ireland from having a hard border, the Telegraph reported.

The option floated by Prime Minister Theresa May that the country should remain tied to EU beyond December 2020 would only be an "alternative to the insurance plan insisted by Brussels", he said.

The Telegraph, often a mouthpiece for the right wing of the Conservative Party, said that Mr Raab's comments would be welcomed by pro-Brexit MPs.

Bloomberg reported late last week that Mrs May is said to be ready to ditch one of her key Brexit demands to resolve the vexed issue of the Irish border and clear the path to a deal. Her fix could result in Britain being tied indefinitely to the EU's customs rules.

Mr Raab's comments were published hours after hundreds of thousands of demonstrators took to the streets of west London to protest against the Brexit vote and the government's subsequent handling of it.

The march was called by People's Vote, a group that's campaigning for the public to have a say on any final Brexit deal, so that the government can't force it through Parliament.

Organisers are talking to 50 Tories including five frontbenchers who might back a second referendum, the Times reported.

The same newspaper also suggested there's almost enough discontent within the Conservative Party to trigger a challenge to Mrs May's leadership.

As many as 46 lawmakers in the House of Commons sent a letter to the backbench 1922 Committee seeking a contest, two short of the number needed.

An unspecified number of Cabinet ministers would vote against her in a leadership ballot, the newspaper said.