Civil servants have threatened ministers with legal action over the Government's Rwanda Bill, warning that senior staff in the Home Office could find themselves in breach of international law.
The FDA union, representing senior civil servants, has written a pre-action legal letter to the Home Office saying that officials could be in breach of international law if they implement the Rwanda scheme.
It has also warned they could be in violation of the civil service code if they follow demands from a minister to ignore an urgent injunction from Strasbourg banning a deportation - something which could leave them open to prosecution.
The civil service code says that officials "must comply with the law". The Government has previously confirmed this includes international law.
Civil servants have threatened ministers with legal action over the Government's Rwanda Bill
PA
The letter, addressed to James Cleverly, demands clarity on the situation and asks him to either amend the legislation or change the civil service code.
The Safety of Rwanda Bill says it is for Government ministers to make decisions on whether or not to comply with decisions from Strasbourg.
But the letter from the FDA, seen by the Guardian, says it is concerned that "if ministers instruct civil servants not to comply with an interim measures indication, they will be putting the UK in breach of international law."
The Bill is due to return to the commons next week, and the Government is expected to try and begin the first flights to Rwanda just days after it has passed into law.
But the FDA warned it "may require legal proceedings" to clarify the matter.
FDA General Secretary Dave Penman noted in his letter that the Government has acknowledged that there is a problem and said it would issue draft guidance to make it clear that it was the responsibility of civil servants to implement decisions on the issue.
LATEST DEVELOPMENTS:
In a letter sent in January, Matthew Rycroft, the top civil servant in the Home Office said: "Given the nature of removal flights, officials should be available to advise ministers at short notice and during evenings and weekends. Home Office officials shall proceed with removal if the relevant minister approves that course of action."
But Penman dismissed the guidance as inadequate.
The letter adds: "Ministers do not employ civil servants and cannot unilaterally change or alter their terms of service.
"The guidance is erroneous in law and gives serious uncertainty for civil servants, and would foreseeably place them in an exceptionally difficult position".
A Government spokesperson said: "Matters of international law are rightly a matter for ministers.
"In the event that the minister decides, in the light of full policy, operational and legal advice, not to comply with a rule 39 indication in an individual case, it is the responsibility of civil servants – operating under the civil service code – to implement that decision."