Britain will be less safe from international criminals, would be diminished on the world stage and suffer economically if it votes to leave the European Union, the campaign to retain ties with Brussels has warned.
At a launch event for the Britain Stronger In Europe campaign, former Association of Chief Police Officers president Sir Hugh Orde warned that "villains" would come to the UK to escape justice if the country pulled out of EU-wide agreements on extradition and sharing evidence.
The In campaign's figurehead, businessman Lord Rose, warned that a vote to leave the EU would be a "leap into the dark", putting the country's prosperity and security at risk.
Sir Hugh, the former chief constable of the Police Service of Northern Ireland, put the dangers of a British exit in stark terms.
Speaking at the launch event in east London, he said: "If I was a villain somewhere else in Europe and I was escaping justice, I would be coming here because it's going to take a lot longer to get you back."