The study warned around 1.2 million jobs will vanish across the 27 remaining EU countries if Brussels fails to reach a trade agreement with the UK.
Irish and Spanish farmers will suffer from a hard Brexit alongside the German car industry and businesses across France and Italy and beyond, according to the report by the Centre for Economic Policy Research (CEPR).
And CEPR warned of more than 290,000 job losses in Germany and approximately 140,000 in each of France and Italy.
But the Republic of Ireland would be worst hit relatively by a no deal situation as more than 50,000 jobs could be lost – more than 2.5 per cent of the workforce.
The report says: “The EU27 stands to lose considerably more than previously thought.”
Campaigners have accused Brussels negotiators of putting more than one million jobs at risk across Europe by refusing to open trade talks instead focusing on the so-called Brexit divorce bill.
Former Labour MP Gisela Stuart, chairman of the Change Britain pressure group, said: “With the EU in the midst of a youth unemployment crisis, it would be irresponsible for politicians in Brussels to refuse a deal which could then see over one million jobs lost in Europe.
“It’s yet further evidence why it’s in the EU’s interests to strike a trade deal with the UK. Any attempts to delay trade talks will only be to the detriment of EU businesses.”
Eurosceptic Tory MP Sir Bill Cash warned of “very adverse consequences” for the EU if there is no deal.
He said: “Their attitude is completely and totally counter-productive.”
Gerard Lyons, co-founder of Economists For Brexit, said: “There is no doubt that in economic terms, once the politics have been taken out of it, it is in the European Union’s best interests to have a deal with the UK.
“It is in everyone’s interests to do a free trade deal. But in terms of the job losses, I would be very wary, because I think the UK can do very well.”
Brussels negotiators said they would not start trade talks with their British counterparts until there had been “sufficient progress” on payment of the Brexit divorce bill, citizens’ rights and the Irish border.