A new French migrant detention centre, funded by the UK, is facing a legal challenge that could delay its opening and impact a £660m deal aimed at reducing illegal crossings of the English Channel. The lawsuit, filed by an environmental group, argues the centre violates local planning rules and poses health risks. The UK Home Office has linked funding to the centre's operational success, while the French government has not disclosed ongoing costs. The centre is expected to focus on detaining migrants from several countries before deportation.