Mass migration to the United Kingdom has been found to cost the Exchequer billions of pounds in a new analysis of academic studies just days before Britain’s referendum on the European Union.

Only a minority of migrants are net financial beneficiaries to the United Kingdom, and overall migrants themselves cost billions of pounds every year. The new study by Migration Watch, released today has found the true cost of migrants is between four and seventeen billion pounds annually.

Despite claims to the contrary, there was also no evidence found that supported the idea that migrants boosted Gross Domestic Produce (GDP) per capita. Citing research by the House of Lords and a 2008 report by National Institute of Economic and Social Research found there was “no evidence that there was any significant economic benefit for the existing UK population”.

Commenting on the new report, Migration Watch boss Lord Green of Deddington said: “There has been a lazy assumption in much recent comment that immigrants are unquestionably an economic benefit to the UK but this very much depends on where they came from and when they arrived.

“Of course many immigrants are hard workers and valuable contributors to our society and EU migrants are often particularly valued by their employers. However, in the context of the referendum debate, the overall economic impact of EU migrants is a relatively small part of the picture”.

The Migration Watch report makes a clear distinction between arrivals from the most developed nations such as the original member states of the European Union including France and Germany which benefit the treasury. On the other hand are migrants from the newer EU nations, which take more out of the Exchequer than they pay in.

The report slams official government figures as “completely misleading”, as when the state calculates the cost of migrants — and claim them as “net fiscal” contributors — it excludes spending on housing benefits and other welfare.

One key area the report establishes is that the longer the time-frame studied, the greater the cost of migration. In this regard, the Migration Watch report mirrors the findings of a Swedish economist and business professor who assessed the lifetime cost of migrants coming to his country.

Looking at the migrants which arrived in Sweden during just the migration crisis of 2015, professor Jan Tullberg assessed social assistance, housing, and pensions and deducted those from the value of tax migrants might on average pay over their lifetimes. At the conclusion of the study, the professor put his “conservative” figure at 583 billion kronor — around £48 billion.

The cost was equivalent to 14 years of defence expenditure for Sweden, for just one year of mass migration.