A former senior Border Force and immigration officer told The Sunday Telegraph: “It is a weakness in the current system but it’s difficult because individual countries’ criminal records databases are not networked. Even if they were to be, it raises quite a big privacy issue.”

It is understood that officials considered tougher visa requirements when the post-Brexit rules on criminal convictions were introduced. This included the possibility of requiring travellers to the UK to get a police certificate confirming they had no criminal record before getting a visa.

“It’s tricky because it would bring the visa system to a grinding halt in places like India and Pakistan because it would take so long to furnish those certificates. And then there would be forgeries,” said the former officer.

Among those who have been banned from the UK are well-known people with convictions such as boxer Mike Tyson, who was barred due to his conviction for rape, and rapper Snoop Dogg for a previous case of violent disorder.

Most prolific countries

The ACRO data obtained by The Telegraph shows the top three nations for murder or manslaughter in the past three years were Romania (307 cases), Lithuania (93) and Poland (83). For rape, it was Romania (235), Poland (121) and Lithuania (41). For child sex offences, it was Romania (216), Poland (203) and the Czech Republic (77).

A Home Office spokesman said: “Those applying for a visa to come to the UK are required to declare any criminal convictions and are subject to checks against UK police databases, watchlists and immigration databases. They may be refused if they have a criminal conviction, a history of serious or persistent offending or have failed to declare convictions.

“Our police also carry out routine checks for overseas criminal convictions on foreign nationals who are arrested, and where serious convictions are found, individuals are referred to Immigration Enforcement for deportation consideration.”

A spokesman for ACRO said: “The UK has well-established mechanisms for exchanging information on criminal records with other countries. This helps UK police pursue criminal investigations and safeguard communities.”