Reform UK has said a future Reform government would avoid placing new migrant detention centres in constituencies with a Reform MP or in council areas controlled by the party, and would instead prioritise Green-held areas for the sites, triggering accusations of political punishment days before voters go to the polls.

The party’s home affairs spokesman, Zia Yusuf, said the approach would reflect what he called “democratic consent”. In a statement posted online, he said: “A Reform government will not put any migrant detention facilities in any constituency with a Reform MP. Nor will we put them where Reform controls the council.”

He added that Reform would “prioritise Green controlled parliamentary constituencies and Green controlled councils”, arguing that the Greens support “open borders”.

The announcement comes three days before elections on Thursday, when voters across the UK will take part in English local elections, the Scottish Parliament election and the Senedd election.

Reform also launched a campaign website, branded “Vote Green Get Illegals”, which includes a postcode checker and an interactive map showing areas the party says would be prioritised for detention centres under its plans. The site says Reform wants capacity to detain “at least 24,000 illegal migrants at a time” and links to a draft Mass Deportation (Detention) Bill.

That draft bill proposes requiring the home secretary to build detention centres in specified areas and to provide at least 24,000 immigration detention places in total. It also contains provisions that would disapply or override parts of existing planning, procurement and detention law in relation to the construction and operation of the centres.

The document is a party proposal, not government policy or law, and the list of areas where centres would be built has not yet been filled in.

The Green Party accused Reform of using inflammatory rhetoric to distract from other policies. Green co-deputy leader Mothin Ali said: “Reform keep making abhorrent announcements to distract voters from the fact they want to privatise the NHS.”

Scottish Green co-leader Ross Greer said the proposal amounted to a threat to voters. “Reform are essentially saying ‘If you don’t vote the way we want you to, we will punish you’,” he said, describing the move as “Trumpesque”.

Labour chair Anna Turley said: “This grotesque policy reveals Reform’s contempt for all voters – including their own.” She said threatening to punish communities for how they vote was a breach of democratic principles.

Criticism also came from parts of the political right. Former Conservative minister Simon Clarke said the proposal looked like an abuse of ministerial power for political purposes and suggested it would be vulnerable to legal challenge.

The row marks an escalation in Reform’s immigration platform, which has focused in recent months on mass detention and deportation. Last year the party said it was prepared to deport between 500,000 and 600,000 people over five years and to create detention capacity for 24,000 people. In February, Reform proposed a new “Deportation Command”, which critics compared to the US immigration enforcement model.

The siting pledge goes further by explicitly linking the location of detention facilities to how areas vote.

Reform’s website says the policy is aimed in particular at places represented by or projected to elect Green politicians. The party has increasingly treated the Greens as an electoral rival in some parts of the country, especially after the Greens’ Westminster by-election win in Gorton and Denton in February.

The party’s argument is that communities represented by politicians who take a more liberal position on immigration should be first in line to host detention infrastructure. Yusuf said in one post: “Put simply, if you vote in a Reform council or Reform MP, we guarantee you won’t have a detention centre near you. If you vote Green, there’s a good chance you will.”

Official figures underline the scale of the plan. Home Office statistics show 2,090 people were being held under immigration powers in the UK on 31 December 2025. Reform’s target of 24,000 detention places would therefore require an estate more than 11 times larger than the number detained at that point.

In the year ending December 2025, 22,996 people entered immigration detention, while 51% of those leaving detention were released on immigration bail rather than removed from the UK. The Home Office reopened Campsfield Immigration Removal Centre in December with 160 bed spaces, rising to a planned 400, illustrating the gap between current expansion and the scale of Reform’s proposal.

The wider migration debate has remained politically charged. Home Office figures show 46,000 irregular arrivals were detected in the year ending December 2025, including 41,000 by small boat. The government has also said nearly 60,000 illegal migrants and foreign national offenders have been removed or deported since the July 2024 general election.

But Reform’s critics say the issue in this case is not only immigration policy, but the principle of allocating controversial state facilities according to electoral support.

The party’s draft legislation would also seek to limit the scope for legal challenge, stating that courts “must not question” the exercise of powers under the proposed Act. Legal and political critics said such provisions, along with the proposed disapplication of planning and other laws, raised serious questions about whether the scheme could ever be implemented.

As of Monday afternoon, Reform had not set out which specific constituencies or council areas would be named in the bill, saying the list would be inserted later.

With campaigning entering its final days before Thursday’s elections, the dispute has quickly become one of the sharpest flashpoints of the week, exposing both the increasingly confrontational tone of the immigration debate and the growing competition between Reform and the Greens in parts of the country.