Hundreds of migrants have been moved out of an immigration centre in Kent following concerns it had become dangerously overcrowded.

Immigration minister Robert Jenrick said the number of migrants at the Manston migrant processing centre had “fallen substantially” on Tuesday, with more expected to be moved on Wednesday.

It came after the situation was branded a “breach of humane conditions” on Monday, with 4,000 people being held at the site.

The exact number to have been relocated has not been confirmed, but Sir Roger Gale, the Conservative MP for the North Thanet constituency which includes Manston, said “several hundred” had already been moved.

The union representing Border Force staff working at the site said earlier on Tuesday that the Home Office hoped to take 400 people out of the site.

Two coaches with heavily tinted windows were seen leaving the centre at around 4.15pm on Tuesday. It appeared the buses were full of people.

Another coach entered the site at around 4.25pm.

Mr Jenrick said: “Thanks to the hard work and professionalism of Home Office and Border Force staff, military personnel and our contractors we have made good progress.

“Numbers of migrants have fallen substantially today (Tuesday) and we expect them to do so again tomorrow.

“Unless we receive an unexpectedly high number of migrants in small boats in the coming days, numbers will fall significantly this week.

“It’s imperative that the site returns a sustainable operating model and we are doing everything we can to ensure that happens swiftly.”

It is unclear whether those moved from Manston will be taken to hotels or alternative accommodation.

The site, located at a former Ministry of Defence fire training centre, opened in January 2022 and was designed to hold up to 1,600 people for no more than 24 hours.

No 10 said Home Secretary Suella Braverman told the Cabinet that “large numbers” of people were being taken from Manston to other accommodation, in a bid to “help relieve pressure”.

Some families were said to have been sleeping on the floor and there were reports of outbreaks of disease.

The British Red Cross said “the serious problems at Manston are indicative of the wider issues facing the asylum system”.

Alex Fraser, director of refugee services and restoring family links at the charity, said: “The UK Government needs to urgently look at ways of reducing the backlog of asylum decisions, including making quicker decisions for nationalities who typically have their asylum claims approved, and providing more safe routes so people who have been forced to leave their homes do not have to make dangerous journeys and gamble with their lives.

“Our country has a proud history of helping people fleeing war and persecution. It doesn’t matter how you got here, everyone deserves to be treated with compassion and humanity once you’re on our shores.”

Meanwhile, a recent resident of the centre reportedly described the conditions there as “like a zoo”, with 130 people forced to share a single large tent.

Ahmed (whose name has been changed) told the BBC: “For the 24 days I’m in there, I can’t call to my family to say to them I’m dead, I’m living – they don’t know anything about me.

“All people in there, they have a family. They should know what is happening to us.”

Almost 40,000 people have crossed the English Channel in small boats so far this year.

Downing Street said the Prime Minister told his Cabinet at a meeting on Tuesday that the UK would always be a welcoming country, while Ms Braverman said a “whole Government approach” would be needed to tackle the migrant crisis.

Meanwhile, counter-terrorism police have taken over the investigation into the firebombing of an immigration processing centre in Dover, Kent, on Sunday, which detectives believe was sparked by “some form of hate filled grievance”.

Andrew Leak, 66, from High Wycombe in Buckinghamshire, is believed to have killed himself after throwing two or three “crude” incendiary devices.

Detective Chief Superintendent Olly Wright, head of Counter Terrorism Policing South East (CTPSE), said: “What appears clear is that this despicable offence was targeted and likely to be driven by some form of hate filled grievance, though this may not necessarily meet the threshold of terrorism.”

Facebook posts on an account under the name of an Andy Leak from High Wycombe contain anti-Muslim sentiments and complaints about people claiming benefits if they do not speak English.