The UK’s ability to track suspected terrorists and major criminals is at risk because of Brexit, Dominic Raab has admitted for the first time.

Full access to vital EU crime-fighting measures – sharing alerts, passenger name records, and fingerprint, DNA and vehicle registration data – could be lost, the foreign secretary told MPs.

The warning came in answer to a question from Theresa May, who had made security co-operation a key aim of her Brexit negotiations. She warned the measures “keep us safe”.

In the Commons, the former prime minister urged Mr Raab to be “much clearer” about intentions for a security partnership, which has been all-but ignored in the fears about lost trade.

She pointed to passenger name record (PNR) data, the Prüm Convention and the upgraded Schengen Information System (SIS II), all of which the UK enjoyed access to as an EU member.

But Mr Raab warned of “difficulties” with Brussels, saying: “They claim that some access to some of the instruments is conditional on accepting free movement.”

He declined to say the UK would remain in any of the data-sharing tools, saying only: “We will be looking forward to securing appropriate relations with the EU.”

The government had already accepted it will crash out of Europol and the European Arrest Warrant, but was expected to fight to retain the benefits of other crime-fighting databases.

Existing arrangements will continue in the transition period – until the end of 2020 – but Ms May protested that what happens next had only been mentioned in passing.

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“Will the government make much clearer publicly its intentions for that treaty in regard to key instruments that keep us safe, such as PNR, Prüm and SIS II?” she asked.

“And what is the final date on which the treaty can be achieved such that it will become operational on January 1 2021?”

However, Mr Raab, in a statement on Boris Johnson’s negotiating aims – including a refusal to extend the transition period – ignored the second question altogether.

PNR data helps to flag people across the EU who are involved in terrorism and serious crime, including victims of trafficking and individuals at risk of radicalisation.

The UK has stressed the importance of maintaining its current access – but other countries with agreements on PNR, such as the US, do not enjoy the same level of co-operation.

Prüm allows the fast-track exchange of fingerprint, DNA and vehicle data. UK access has been held up by its refusal to exchange DNA profiles on people arrested but not convicted of any offence.

SIS II enables police to log and view alerts on missing and wanted individuals, as well as lost and stolen objects, including clear instructions on what to do.