Migrants are seen on the UK Border Force rubber dinghy, after they were picked up at sea while attempting to cross the English Channel, and brought to the Marina in Dover, southeast England, on June 16, 2022. AFP
Net migration into the UK -- the number of people arriving to start new lives, minus those leaving -- stood at 504,000 in the 12 months to June, the Office for National Statistics (ONS) said.
That was up sharply from 173,000 in the previous year, and was also driven by the resettlement of Afghan refugees, plus a new visa route for UK passport holders living in Hong Kong.
Students entering Britain after the easing of pandemic lockdown curbs were another factor, the ONS said.
"A series of world events have impacted international migration patterns in the 12 months to June 2022. Taken together these were unprecedented," commented Jay Lindop, director of the Centre for International Migration at the ONS.
They have "all contributed to the record levels of long-term immigration we have seen", she said, while noting it was "too early to say whether this picture will be sustained".
The figures risk complicating the political debate over immigration six years after Britain voted to leave the European Union, in a backlash against the free movement of people across the bloc.
Interior minister Suella Braverman, a hardline Brexiteer, on Wednesday admitted the government had "failed to control our borders".
She vowed anew to tackle the isssue of record numbers of migrants crossing the Channel from France, but struggled to explain to MPs how would-be asylum seekers fleeing war and persecution could now enter Britain legally.