Sussex Police "made a serious mistake" when issuing a formal warning to an MP and should consider withdrawing it, a parliamentary committee has said.

The Commons Privileges Committee said the force carried out "a contempt of Parliament" by sending a public information notice to East Worthing and Shoreham MP Tim Loughton warning him not to harass a constituent.

The force were criticised for their “inability to recognise” that freedom of speech of Parliament was part of the law they should uphold.

Sussex Police responded to the committee report by saying they would give it “careful and serious consideration”.

The former children’s minister said the police information notice (PIN) was issued by the force after he sent a constituent a copy of Hansard - the record of parliamentary proceedings - containing a speech he made to the House of Commons about a long-running dispute between them.

Police information notices are used to make someone aware that their actions have prompted an allegation of harassment but don’t constitute threat of formal legal action and are issued with the intent of preventing further escalation of an issue.

The Committee MPs said: "We do not consider further action is necessary in this case, subject to an appropriate response from Sussex Police.

"Nonetheless, we deplore Sussex Police's inability to recognise that the freedom of speech in Parliament, and the ability of Members to carry out their functions without unfounded legal threats, are themselves part of the law which the police uphold."

A Sussex Police spokesman said: “We dealt with this as an operational matter, as we would any other, and in issuing PIN notices to all parties, our aim has always been to reach a resolution, treating everyone fairly and in accordance with the law.

“The question of Parliamentary Privilege and associated legislation is highly complex, as was evidenced by the debate that took place at the Committee of Privileges.

“The Committee recognises that our breach was inadvertent.

“We will give the report and any recommended action careful and serious consideration.”