The human rights of EU nationals resident in the UK must not be used as bargaining chips in Brexit negotiations, a parliamentary watchdog has warned.
The Joint Committee on Human Rights has urged Prime Minister Theresa May to secure the status of the estimated 2.9 million people from the EU living in the UK at the start of the Article 50 negotiations by reaching a separate preliminary agreement on the matter.
An interim report by the cross-party parliamentary committee also calls on Mrs May to clarify whether she intends to strip any rights from the EU nationals resident here.
The committee is demanding that any future legislation should include safeguards for EU nationals, and Parliament should have the final say on any changes to their status.
The report notes that International Trade Secretary Liam Fox has reportedly described EU nationals in the UK as one of the "main cards" in Brexit negotiations.
Committee chairwoman and Labour MP Harriet Harman said: "The Government must not use human rights as a bargaining chip.
"Moreover, the Government will continue to have obligations under Article 8 of the European Convention on Human Rights, as we set out in our report.
"The UK Government could not deport the large numbers of EU nationals currently in the UK.
"In the unlikely and unwelcome event that the Government sought to deport EU nationals, there could be the potential for significant, expensive and lengthy litigation, leading to considerable legal uncertainty for a prolonged period of time.
"These cases would have the potential to clog up and overwhelm the court system."
The report states the Government would not be able to establish a rule that would allow the deportation of EU nationals merely on the grounds that they had only been resident for a fixed period of time.
Other factors, such as family connections, and the residence rights of children, would be relevant, and each case would need to be considered on its own facts, it said.
The committee is calling on the Government to lay out a detailed list of fundamental rights currently guaranteed to such people by virtue of the UK's EU membership and what approach it intends to take towards them.
The report also states any changes to the status of EU citizens must be voted on by both Houses of Parliament, and not put through in secondary legislation.
"The Government should issue detailed statutory guidance on the status of existing case law. It will also have to determine how it will approach the status of future EU law and the Court of Justice of the European Union decisions to ensure that it is not isolated from developments emanating from the EU," the report states.
The committee said the Government should continue to impose human rights clauses in trade agreements after Brexit.
Ms Harman said: "Any dilution of human rights standards would be extremely undesirable.
"There is an argument to be made that if the UK enters into any new agreements, this is an opportunity to raise standards."
A Government spokesperson said: "The UK has a long standing tradition of ensuring our rights and traditional liberties are protected domestically and of fulfilling our international human rights obligations. The decision to leave the European Union does not change that.
"The Prime Minister has been clear that she wants to protect the status of EU nationals already living here, and the only circumstances in which that wouldn't be possible is if British citizens' rights in European member states were not protected in return."