FILE PHOTO: Danish police.
© Sean Gallup / Getty ImagesFILE PHOTO: Danish police.
Danish police are trying to curb gang violence as criminal bosses often rely on teenagers from Sweden to do their bidding

Denmark is stepping up security at the border with Sweden after a series of shootings involving alleged hitmen - several of whom turned out to be minors - who had arrived from its Nordic neighbor.

Speaking to the broadcaster TV2 on Friday, Danish Justice Minister Peter Hummelgaard described the situation as "serious," adding that the Danish authorities are ramping up the physical presence of law enforcement at the border, particularly on trains crossing the Oresund Strait that separates the two countries. Police are also increasingly using security cameras.

Swedish Justice Minister Gunnar Strommer described the new measures as a natural step. "It is new development that criminal groups operating in Denmark recruit contractors in Sweden. Of course, this is serious and we have a strong common interest... in stopping this," he said.

Hummelgaard acknowledged that gang violence involving mercenaries has escalated in recent weeks, describing it as a "disgusting phenomenon." He also noted that one facet of the problem is that hired Swedish child soldiers" come to Copenhagen to carry out tasks in connection with gang conflicts. According to him, the "strings" in these conflicts are pulled by people from the non-Western world, in countries such as Lebanon, Iraq, and the United Arab Emirates. "We don't want to put up with this," he stressed.

Sweden, meanwhile, has long been plagued by violence and elevated crime levels in many largely immigrant neighborhoods.

Last week, Denmark was rocked by a string of violent incidents. On Thursday, a 43-year-old man was killed and a 42-year-old woman injured in a shooting in northwestern Copenhagen, with the assailant still at large. Meanwhile, Danish police have arrested two Swedish nationals - aged 17 and 16 - suspected of two other shootings in Copenhagen, and another 17-year-old suspected of a shooting in the town of Kolding.

Two other Swedish nationals are also suspected of throwing a grenade into a kiosk in Copenhagen. They were extradited last week.

On Friday, TV2 published an investigation which provided a glimpse into the bustling criminal job market. Social media is rife with offers promising large sums of money for murder, vandalism and other types of violence. For example, a job with the title "shot in the head" pays around $47,500, while those willing to throw a grenade at an unspecified target could potentially earn $19,000.