A new report from the national commissioner of police in Denmark states organized migrant criminal gangs have become more numerous, more specialized and pose a greater threat than ever before.

A large police operation in February of 2015 in the region of Zealand and Lolland-Falster in Denmark led to the search of over 60 addresses by over 400 officers. the raid revealed the largest smuggling ring in the history of the country and consisted primarily of foreign migrants.

Charges against foreign criminals have more than doubled since 2009 and police worry that they are to blame for rising crime rates as domestic offending is declining, reports Danish paper Berlingske.

National Police Commissioner Jens Henrik Højbjerg doesn’t see any decrease in foreign criminality in the near future. “As long as there is such large wealth disparities in Europe, there will be an incentive to leave their own country and commit crimes elsewhere.

“There may be more to be had in the richer countries, and one must assume that this is not just a phenomenon that stops by itself,” he said.

By far the biggest section of foreign criminals come from Romania according to the National Police Commission, who said that most of the crimes committed are simple retail theft, computer fraud, credit card scams and home burglaries. The surge apparently matches what former UKIP leader Nigel Farage warned about credit card and ATM scams primarily committed by Romanian nationals in the UK.

The Danish police also warn that the criminals are becoming ever more interconnected and more sophisticated, leading to the rise of a more formal crime structure within Denmark.

Though the number of crimes is rising, the number of known criminals is not rising at the same rate, leaving police suspecting that foreign gang members commit crimes at a significantly higher rate. In one case 76 Romanians were thought to be behind 5,541 cases of credit card fraud in 2015 alone.

Danish People’s Party spokesman, Peter Kofod Poulsen has said that despite many of the criminals being European Union citizens, Denmark should look into increasing border security. “I think it makes a huge difference that you risk being snatched at the border,” he said.

Denmark has recently pushed for the continuation of border controls within the Schengen free movement area along with several other countries as the European Union looks to lift the suspension of the open borders agreement in November.

Foreign crime from migrants is also on the rise in several countries in the European Union. In Germany recent statistics showed a disproportional number of crimes being committed by asylum seekers and other migrants.