France would relocate its migrant camp from Calais to Britain and roll out “a red carpet” for bankers fleeing London if the UK leaves the EU, according to Emmanuel Macron, the French economy minister.

Speaking ahead of an Anglo-French summit, Mr Macron said the bilateral relationship could change abruptly in the event of a Brexit, including the creation of new obstacles to trade between the two countries.

Mr Macron said that Brexit could scupper a bilateral deal with France, known as the Le Touquet agreement, that allows Britain to carry out border controls — and keep unwanted migrants — on the French side of the Channel.

In an interview with the Financial Times, he also said he expected financial services workers in London to relocate to France once their institutions lost the “passport” rights that allow them to operate across the EU.

“The day this relationship unravels, migrants will no longer be in Calais and the financial passport would work less well,” Mr Macron said.

Echoing David Cameron’s invitation to French companies to relocate across the Channel when France raised taxes in 2012, Mr Macron said: “If I were to reason like those who roll out red carpets, I would say we might have some repatriations from the City of London.”

Mr Macron warned that Britain would lose full access to the single market if it left the EU. “People deciding to leave the single market will not be able to secure the same terms.”

He added that the EU’s “collective energy would be spent on unwinding existing links, not re-creating new ones” if British voters rejected membership.

Mr Cameron was accused by Tory Eurosceptics of “scaremongering” when he claimed that the Calais “Jungle” camp could move across the Channel. Now a leading French minister has confirmed it could happen.

The prime minister is working with the French government, including President François Hollande, to co-ordinate a message aimed at persuading British voters they are safer within the EU.

Meeting in Amiens in northern France on Thursday, Mr Cameron and Mr Hollande will say that the “EU gives greater security and greater capacity to project power”. They will commit to a “relentless” battle against terrorism.

The two leaders will agree to a joint £1.5bn investment in a new phase of development for a military drone as well as agreeing a further exchange of information to combat terrorist attacks.

Pressure is mounting on the French government to prevent thousands of refugees fleeing wars and poverty from setting up base in makeshift camps before attempting to cross the Channel to the UK. French authorities began dismantling part of the so-called “jungle” this week, relocating migrants in nearby shipping containers. Politicians including Marine Le Pen, the far-right leader, and Xavier Bertrand, the centre-right chairman of the Nord Pas de Calais region, have requested the border be moved to Dover as part of a longer-term solution.

The day this relationship unravels, migrants will no longer be in Calais, and the financial passport would work less well

Mr Macron said the EU as a whole would be weakened as a military, diplomatic and economic powerhouse if the UK left. But whatever the outcome of the British referendum in June, he said the EU would need to reignite its integration process because the Brexit debate would have durably hurt the bloc’s unity. “The EU has no choice but to become a true military and diplomatic power, something it has been always reluctant to be, mostly by lack of ambition,” he said.

“If the UK decides to stay, we avoid the worst case scenario but we find ourselves in a situation where the UK will demand the implementation of the new terms it has negotiated with Brussels. Other countries may be tempted to do the same,” the minister said, pointing to the rise of anti-EU parties in France, Poland, Spain, the Netherlands and Germany.

Since 2008, the solidarity among EU members had been severely shaken by crises that did not originate in the bloc — the collapse of Lehman Brothers and the refugee crisis, said Mr Macron. But the solutions are through more risk sharing and co-operation, not a return to nationalistic policies, he insisted.

“It’s only at a European level that we can manage the sovereign debt risk or the banking risk,” Mr Macron said. “The refugees crisis shows we can’t be isolated from the world’s geopolitical troubles. It’s true that the handling of this crisis is appalling. But the response can only be a European one, not a national one, with a co-ordinated diplomacy and border controls.”

Mr Macron refused to blame Germany for acting unilaterally on refugees and energy, saying: “We could say the same of France about other matters.”

Brussels, however, is failing to protect European industries and jobs, he said. “Steelmaking is emblematic of this naivety: we ask our companies to restructure, we ask employees to work more for less money because there is overproduction but then we’re unable to defend them from cheaper Chinese imports,” he said. “We are insane.”