Boris Johnson, Britain's Foreign Secretary, arrives for a cabinet meeting at 10 Downing Street in London, September 21, 2017. [Photo/Agencies]

LONDON - Britain's Foreign Secretary Boris Johnson laid down four demands Saturday in what his second controversial Brexit intervention within days.

Elsewhere, a group of leading Conservatives urged Prime Minister Theresa May to walk away from Brexit talks altogether if European Union negotiators fail to start talks on a future trade deal by Christmas.

The moves, widely reported in Britain's Saturday morning national newspapers, came as thousands of Conservatives started to converge on Manchester for the party's annual conference which starts Sunday.

May faced calls to fire Johnson after his controversial intervention with an article he penned just before her keynote Brexit speech in Florence.

In his latest intervention, Johnson has laid out what are four red-lines for Brexit. He has told the tabloid Sun newspaper a Brexit transition period must be a maximum of two years, not a second more. He also said Britain must refuse to accept new EU or ECJ (European Court of Justice) rulings during a transition period.

Johnson also said there should be no payments for single market access when the transition ends, and Britain must not agree to shadow EU rules to gain access to its market.

He said in an interview with the newspaper's respected political editor Tom Newton-Dunn: "When it comes to paying for access to the market, that won't happen any more than we would expect them to pay us for access to our market. There is no point in coming out of the EU and then remaining in rotational orbit around it. That is the worst of both worlds."

Newton-Dunn said all of Johnson's demands go further than the agreed position of May's governing executive, her cabinet of ministers.

It now risks reopening the bitter feud among her senior ministers, commented Newton Dunn.