Net migration rose to 606,000 in the year to December 2022, official statistics show.
The figure smashes the previous post-war high of 504,000 in the year to June last year – and comes despite a Tory 2019 manifesto commitment to “bring overall numbers down”.
Net migration is the annual number of people arriving in the UK when both immigration and emigration are taken into account.
The figures, published by the Office for National Statistics (ONS) show that total long-term immigration was estimated at around 1.2 million in 2022, while emigration was 557,000.
Most people arriving to the UK last year were non-EU nationals (925,000), followed by EU (151,000) and British (88,000), the ONS said.
The body said it was a “unique year” for migration due to “world events” including the war in Ukraine and unrest in Hong Kong.
“Our estimates also show that levels of immigration from non-EU international students, and their dependents, remain high,” it said.
The ONS said the rise could be attributed to increased demand post-pandemic, as well as delayed travel and the new graduate visa route, which allows students to apply to work in the UK for a period of time after completing their studies.
However, it said that despite he rise in immigration last year, its long-term international migration estimates “suggest a slowing in growth over the most recent quarters”.
“This may reflect the temporary nature of these world events, as well as beginning to see higher numbers of international students emigrate. We will continue to monitor these patterns in the coming months.”
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The fresh statistics are likely to draw the ire of Tory backbenches who want to see immigration reduced.
Prime Minister Rishi Sunak is under pressure after he appeared to back away from a commitment made under his predecessor, Boris Johnson, that net migration would fall below 250,000.
Last week he vowed to bring the level of net migration down to below the 500,000 figure he “inherited” upon taking office but would not put a number on the figure he would like to see.
Suella Braverman, the home secretary, has said Britain is at risk of “forgetting how to do things for ourselves” due to a reliance on foreign workers.
On Tuesday, Ms Braverman announced new curbs on international students bringing family members to the UK in a bid to lower the numbers.
But Labour says the reason the government has had to issue so many visas is because of “labour and skills shortages”.
Earlier this week, separate figures seen by Sky News showed a growing number of skilled workers from Africa and Asia are moving to Britain to plug staff shortages, with businesses making use of the new post-Brexit migration system to bring in IT professionals, nurses and accountants.