Reform UK has said it would open migrant detention centres for people awaiting deportation in areas that vote for the Green Party.

The party had previously said it would build removal centres in remote areas of the country if elected, as part of plans to detain up to 24,000 people within 18 months.

Zia Yusuf, Reform UK's home affairs spokesperson, said Green-controlled areas would be prioritised because of what he described as the party's support for "open borders".

A Green Party spokesperson said it was a "disgusting idea" and accused Reform of "making abhorrent announcements in attempts to distract voters" from its other policies.

"We want a fair and managed immigration system," the spokesperson added.

"We recognise we have an ageing population and agree the current system is broken, but we are not into performative cruelty."

Reform UK has also said it would not put detention centres in areas where its own party has an MP, or where it controls the council.

Yusuf said: "Given the Green Party advocate for open borders and for an infinite number of undocumented men to come here, we will prioritise Green constituencies and Green-controlled councils to locate these detention centres.

"This is the fairest approach to ensuring democratic consent for all aspects of our mass deportation programme."

The Green Party has previously said it "wants to see a world without borders" but their leader Zack Polanski told Sky News last year that open borders were "not a pragmatic" solution for a world in "turmoil".

Labour Party chair Anna Turley described the Reform UK idea as a "grotesque policy" and claimed Reform UK leader Nigel Farage wanted to "drive a toxic wedge between our communities" and "doesn't care about fixing the system".

Chris Philp, shadow home secretary, said: "Reform is not a serious party and this is not a serious policy. It is clearly made up on the spot for a social media video."

The Liberal Democrats' home affairs spokesman Max Wilkinson said it was "a squabble between two parties who don't have the solutions to bring about a safe, fair and controlled asylum system in our country".

Meanwhile, Scotland's First Minister John Swinney said it was an "illustration of the dangerous nature of Reform's politics" and an "attempt to divide communities".

Reform UK also said it would introduce a Mass Deportation Detention Act, to give the home secretary powers to stop councils blocking the opening of detention centres.

The party said that people placed in the centres would not be able to leave and would stay there for about two weeks before being deported.

Official figures from the current prison programme show that it costs about £500,000 per bed to build such "closed" facilities - and that is broadly the design standard used for immigration removal centres too.

That means that if the party in government were to build 24,000 new detention spaces to that standard, it would cost about £12bn.

In their 2024 general election manifesto, the Greens called for "an end to immigration detention for all migrants unless they are a danger to public safety".