The campaign to keep Britain in Europe is being part-funded with hundreds of thousands of pounds foreign companies and some of America’s biggest banks, it has emerged.

Figures from the Electoral Commission show that Citigroup and Morgan Stanley donated £250,000 each to the official Britain Stronger in Europe group ahead of the June 23 referendum on Britain's membership of the European Union.

Two other US banks – Goldman Sachs and JP Morgan – donated £500,000 each to the Britain Stronger in Europe campaign before February when donations had to be declared.

Other donations came from France’s Airbus and Eurostar, which gave £7,500 each.