The rights of EU nationals living in the UK are not bargaining chips in Brexit negotiations, a parliamentary watchdog has warned the Prime Minister.

The Joint Committee on Human Rights has told Theresa May to treat as her first priority the status of the estimated 2.9 million people from the EU living in the UK, and reach a separate preliminary agreement on the matter before negotiations begin next year.

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.

Committee chairwoman 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.