The number of migrants to cross the English Channel in small boats since Labour came to power last summer is expected to have reached 50,000.
Home Office data shows 49,797 people had arrived as of Sunday, with Monday’s total due to be released later.
Government minister Baroness Jacqui Smith told the this was an “unacceptable number of people” but pointed to the “one in, one out” returns deal with France as a deterrent.
But the Conservative Party said the migrant crossing totals showed Labour had “surrendered our borders”.
The latest figures come as ministers continue to grapple with how to effectively crack down on people-smuggling gangs – a key pledge of Sir Keir Starmer’s when he became prime minister.
Baroness Smith told Breakfast: “We understand how concerning this is to people.”
She said the migrant crossing figures showed people-smuggling gangs had taken an “absolute foothold in the tragic trafficking of people” in recent years.
But the minister added the government was “making progress” on tackling people smuggling, and people had already been detained under the UK’s “ground-breaking agreement” with France.
The “one in, one out” pilot will see the UK return some migrants to France in exchange for receiving the same number of asylum seekers who are believed to have legitimate claims.
The first returns are due to happen within weeks – but the initial numbers are expected to be small.
The 50,000 figure will cover 5 July 2024, when Labour came to power, to 11 August this year.
Between 5 July 2023 and 11 August 2024, during which time the Conservatives were in power for the most part, there were 36,346 migrant crossings in small boats.
A number of factors affect crossing totals, including where weather conditions are more favourable for attempts.
But the Tories accused Labour of overseeing the “worst illegal immigration crisis in our history”.
“This is a taxpayer-funded ferry service for the people-smuggling trade. Every illegal immigrant should be removed immediately upon arrival,” said shadow home secretary Chris Philp.
The Home Office said it wants to “end dangerous small boat crossings, which threaten lives and undermine our border security”.
“People do not cross the Channel unless what lies behind them is more terrifying than what lies ahead,” said Enver Solomon, chief executive of the Refugee Council charity.
The charity’s frontline workers say the men, women and children travelling in small boats are “often fleeing places like Sudan, where war has left them with nowhere else to turn”, he added.
“To stop smugglers for good, the government must expand safe and legal routes, such as allowing family members to travel to be with their loved ones who are already settled in the UK,” he said.
“Without these measures, desperate people will continue to take dangerous journeys, and the criminal gangs are likely to simply adapt their approaches.”
