“These are people who live outside of society, people who are vulnerable to crime and who can't go to the police. People who work illegally and risk being exploited as cheap labour, and who have to pay too much for accommodation,” Swedish Border Police chief Patrik Engström told radio station Sveriges Radio P4.

“But there are also people who can be enticed or driven towards crime in order to support themselves,” he warned.

Engström explained that police in Sweden are carrying out fewer domestic checks on migrants these days, with the 19,000 done last year several thousand fewer than the year before.

A lack of resources caused by the need to carry out controls at the Swedish border as well as deal with gang-related crime means such checks cannot be prioritized.

On January 1st the Swedish police had more than 12,000 cases of people who were being sought by the Migration Agency (Migrationsverket), and it is not known how many of them remain in Sweden.

Police think that in the future more people will choose to stay in Sweden in a hidden manner because of new rules that mean those who have an asylum application rejected will no longer be entitled to food and lodging.