An Oxford University study say the number of foreign-born residents in England has increased by more than half a million in three years— a finding that will fuel debate about immigration ahead of the upcoming election.

The study by the university's Migration Observatory says around two-thirds of the 565,000 migrants thought to have come to England between 2011 and 2014 were born in other EU countries.

The observatory estimates that puts the total number of foreign-born residents at 7.9 million. In 2001, the number of migrants was 4.6 million.

The rate of immigration in England, whose population is about 53 million, has stirred passions ahead of the election, with at least one party, the U.K. Independence Party, arguing it is too high.