It revised the figure upwards by 139,000 from what was already a record when released in May, citing “unexpected patterns” in the behaviour of migrants.

Sunak has long described regular immigration levels as “too high”.

His party won by a landslide under the leadership of Boris Johnson at the last election in 2019, largely on a promise to bring net migration numbers down.

The Conservatives have repeatedly promised that leaving the European Union, which ended the free movement of people from member states, would allow the UK to “take back control” of its borders.

But legal migration has soared since Britain formally left the EU in January 2020. In 2021, net migration was 488,000.

Sacked UK minister Braverman attacks PM Sunak as failing and weak

Some Tory backbenchers urged Sunak to “act now” to cut net migration and meet the party’s 2019 pledge.

“This really is ‘do or die’ for our party,” the New Conservatives group of right-wing lawmakers said in a statement.

A spokesperson for Sunak said it was clear net migration “remains far too high” and hinted that further measures to reduce it were on the horizon.

The government has already cracked down on visa applications for dependents of students and is reportedly mulling raising the minimum salary threshold for work visas.

“We believe there is much more to do and where the [visa] system is being abused we will leave no stone unturned in rooting that out,” Sunak’s spokesperson told reporters.

The ONS added though that net migration for the year to June 2023 is estimated to drop to 672,000.

It said 1.2 million people came to Britain during that time, while 508,000 left.

“While it is too early to say if this is the start of a new downward trend, these more recent estimates indicate a slowing of immigration coupled with increasing emigration,” the ONS said.

Sunak fights to save Rwanda migrants treaty; new plan to be ready in ‘days’

Interior minister James Cleverly focused on this lower number.

“This figure is not showing a significant increase from last year’s figures and is largely in line with our own immigration statistics,” the home secretary said.

Most new arrivals were from non-EU countries, including India and Nigeria, continuing a trend seen since the 2016 Brexit referendum.

Study accounted for 39 per cent of non-EU arrivals, while 33 per cent came for work – up from 22 per cent last year. The ONS attributed that rise to more health and care visas, with Britain’s National Health Service under pressure to find staff.

On top of the record number of legal migrants, Sunak is struggling to cut the number of irregular arrivals crossing the Channel from northern France on small boats. More than 28,000 have undertaken the dangerous crossing this year.

The government has deemed such crossings illegal but its much-trumpeted plan to deport asylum seekers to Rwanda was struck down by the courts last week. Sunak has vowed new “emergency” legislation and a revised treaty with Kigali to get flights in the air by the spring.

The Tories, in power since 2010, lag well behind centre-left Labour in opinion polls ahead of an election that must be held by January 2025.

Labour said Thursday’s figures highlighted the government’s “failure” on immigration.