MPs have accused the Government of “complacency” over post-Brexit security links with the EU.

The UK would be less safe if it loses access to key databases and tools used by police to track criminals and terrorists, according to a report from the Commons Home Affairs committee.

It flagged up the Second Generation Schengen Information System (SIS II), which contains 76.5 million alerts on missing and wanted individuals, and lost and stolen objects.

UK authorities searched the database more than 500 million times last year, and senior officers have repeatedly highlighted its importance.

The committee said it was “seriously concerned” about the absence of any reference to SIS II in the political declaration on the future UK-EU relationship.

The two sides have agreed to consider how to deliver capabilities that “approximate” those enabled by mechanisms such as SIS II and the European Criminal Records Information System (ECRIS).

Home Secretary Sajid Javid told the committee last month: “In terms of keeping our country safe, SIS II is a nice-to-have, but our country is still safe even if, for whatever reason, we did not get access to that system.”

But the committee said it did not share this view.

A failure to retain access to SIS II and ECRIS would mean a “significant downgrade” of capabilities at a time when cross border crime and security threats are increasing, its paper warned.

It added: “Losing access would, as the police have warned, make us less safe.”

The report raised concern at a “lack of progress” in negotiations on future security co-operation and warned there was a risk of a “capability gap” in future unless there is a resolution before the transition period expires at the end of 2020.

Labour MP Yvette Cooper, who chairs the committee, said: “We are worried about the prospect of a security downgrade as a result of this deal.

“It doesn’t include the key criminal databases that the police and border force check 500 million times a year to keep us safe.

“Nor is there a security backstop to make sure that the transition arrangements don’t run out before a new security treaty can be implemented

“Continued police and security c-ooperation is in everyone’s interest, but there is far too much complacency.”

She also said it was “ridiculous” that Parliament faces having to vote on the Brexit deal without having seen the Government’s delayed immigration white paper.

Last month an official analysis detailed how, in the event of a no-deal departure, UK agencies would no longer be plugged in to systems for exchanging data including criminal records, alerts on wanted suspects, DNA, fingerprints and airline passenger information, extradition requests would take longer, and co-operation on counter-terrorism and illegal migration would be affected.

The two sides have committed to establishing a “broad” and “comprehensive” security partnership, and the Government says that in a “deal scenario” operational co-operation will continue largely as it does now during the implementation period.

A Home Office spokesman said: “This deal delivers the broadest security partnership in the EU’s history and provides a framework for a future security relationship between the UK and the EU to keep people safe.

“It is in everyone’s interests to combine efforts on security and, whilst our relationship with the EU will change, we have agreed to share vitally important information, including passenger name records, DNA, fingerprints and vehicle registration.

“We will also be establishing a streamlined extradition process so that our law enforcement agencies can quickly investigate and prosecute criminals and terrorists.”