France has accused the UK of “improvising” its handling of Brexit, after Theresa May gave a landmark speech outlining her plans for leaving the EU.

France’s finance minister, Michael Sapin, described the British Government as “helpless” in the face of its departure from the EU, saying it was clear clear from Britain’s fluctuating position that “some of them don’t want” to leave the union.

Speaking to reporters on Tuesday, Mr Sapin said: “It has been a few months since the referendum took place. You might have thought that certain people had prepared for this.

“No-one was prepared. You can see very well that they are improvising, with flip-flopping between accommodating positions... and harder positions, even a 'hard' Brexit.

”All of this shows how helpless the British government is in the face of a situation that some of them didn't want, and that it has created debates within the government which are clearly very difficult."

The comments came as Ms May said in her speech that Britain will pull out of the single market when it leaves the EU, because not doing so would “mean not leaving the EU at all”.

On the customs union, the Prime Minister suggested the UK could negotiate some sort of “associate member” access while retaining the right to carry out its own deals with non-EU nations — in other words, becoming exempt from the “common external tariff”.

In October, French President Francois Hollande — who called the likely hard Brexit the biggest crisis in the EU’s history – demanded that Britain must pay a heavy economic price for leaving the EU.

Supreme Court Brexit Challenge Show all 13 1 /13 Supreme Court Brexit Challenge Supreme Court Brexit Challenge People wait to enter the public gallery outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge Gina Miller, co-founder of investment fund SCM Private arrives at the Supreme court in London on the first day of a four-day hearing Getty Supreme Court Brexit Challenge A man waves the EU flag in front of the Supreme Court Getty Supreme Court Brexit Challenge Satirical artist Kaya Mar poses with two of his paintings in front of the Supreme Court Getty Supreme Court Brexit Challenge Pro-Europe protestors dressed as Supreme Court Justices stand outside the Supreme Court ahead of the first day of a hearing into whether Parliament's consent is required before the Brexit process can begin. The eleven Supreme Court Justices will hear the government's appeal, following the High Court's recent decision that only Parliament can trigger Article 50 Getty Supreme Court Brexit Challenge The eleven Supreme Court Justices will hear the government's appeal, following the High Court's recent decision that only Parliament can trigger Article 50 Getty Supreme Court Brexit Challenge Businesswoman Gina Miller arrives at the Supreme Court ahead of the first day of a hearing into whether Parliament's consent is required before the Brexit process can begin Getty Supreme Court Brexit Challenge Attorney General Jeremy Wright arrives at the Supreme Court in London EPA Supreme Court Brexit Challenge Protesters outside the Supreme Court in London, where the Government is appealing against a ruling that the Prime Minister must seek MPs' approval to trigger the process of taking Britain out of the European Union PA wire Supreme Court Brexit Challenge A protesters wearing a judge's wigs and robes stands outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge A protester holds up a placard outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge Pro-Europe protestors dressed as Supreme Court Justices stand outside the Supreme Court Getty Supreme Court Brexit Challenge A man waiting to enter the public gallery waves a European Union flag outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters

Mr Hollande said at the time: “We need to remain strong. If not, we will threaten the very principles of the European Union. That could lead to other countries or regions wanting to leave the EU to gain so-called benefits but without any inconvenience or rules.

“There must be a threat, there must be a risk, there must be a price. Otherwise we will be in a negotiation that cannot end well.”