Campaigners for Britain to leave the European Union seized on new figures showing net migration from the EU rose to 184,000 last year as evidence that the "system has spun out of control."
The government said estimated net migration of EU citizens in the 12 months to December was up from 174,000 in the previous 12 months, equalling the highest 12-month total recorded.
"That means we are adding a population the size of Oxford to the UK every year just from EU migration," said Boris Johnson, the Conservative former mayor of London, who is spearheading the Vote Leave campaign ahead of Britain's referendum on EU membership on June 23.
The rise was spurred by net migration of 102,000 in citizens of Bulgaria and Romania, but the Office for National Statistics said the change in total net migration from the EU was "not statistically significant."
Immigration is expected to be one of the two main issues - along with the economy - in the final four weeks of campaigning before the referendum.
Johnson claimed that "1.25 million people have been added to the population due to EU migration" since 2004.
He said Britain must "face the fact that the system has spun out of control."
"We cannot control the numbers. We cannot control the terms on which people come and how we remove those who abuse our hospitality," Johnson said. "This puts huge pressure on schools, hospitals and housing."
Nigel Farage, leader of the anti-EU UK Independence Party, said he was "sure the real numbers are much higher."
"Today's disastrous migration figures show once again why we must leave the EU and control our borders," Farage said on Twitter.
James Brokenshire, Britain's immigration minister, accepted that net migration from EU nations was "too high" but warned that leaving the EU was "no panacea or silver bullet, whatever some may suggest."
The government is "committed to reforms to bring migration down to sustainable levels, which is in the best interest of our country," Brokenshire said.
Prime Minister David Cameron, who is campaigning for Britain to remain in the EU, set a target in 2010 to reduce annual net immigration to below 100,000.
Britain's overall net migration rose to 330,000 in the year to December, including net migration of 188,000 from non-EU states, down from 194,000 in 2014.
Estimated total arrivals of EU citizens stood at 270,000 in 2015, up from 264,000 in 2014, while total arrivals of non-EU citizens fell by about 10,000 to 277,000 last year, the ONS said.
In the year to March, about three-quarters of the 826,000 new registrations for national insurance numbers - which allow people to work in Britain legally - were for EU citizens. They included 179,000 for Romanian citizens and 40,000 for Bulgarian citizens, it said.