Spain’s central bank has put a figure on the projected labour shortfall. In a report published in April, it said that the country will need around 25 million immigrants , externalover the next 30 years.

The left-wing Spanish government has also made the economic case for immigrants, with Prime Minister Pedro Sánchez describing them as representing “wealth, development and prosperity” for his country, while on a recent tour of Mauritania, Gambia and Senegal.

“The contribution of migrant workers to our economy is fundamental, as is the sustainability of our social security system and pensions,” he said.

Mr Sánchez’s coalition is hoping that a proposal to legalise the status of up to 500,000 undocumented migrants, mainly from Latin America, will get through parliament. Spain has seen nine such mass regularisations in its democratic era, most recently in 2005 under a previous government led by the Spanish Socialist Workers’ Party.

However, the country’s economic needs contrast with ordinary Spaniards’ perception of immigration. A new poll shows that 41% of people are “very worried”, external by the phenomenon, making it their fifth-biggest concern after inflation, housing, inequality and unemployment.

While only 9% of Spaniards associate immigrants with economic progress, 30% link them to insecurity, and 57% believe that there are too many of them.