Denmark has temporarily reinstated checks at its border crossings with Sweden after a spate of bombings and shootings in the Copenhagen area that authorities say were carried out by members of Swedish gangs.

The spot checks at ferry ports and on trains and vehicles crossing the Øresund bridge separating the Danish capital from Malmö, Sweden’s third-largest city, were aimed at “preventing serious and organised crime from spreading”, the police said. All travellers should be prepared to show identification, they added.

Lene Frank of the national police said: “We are targeting organised crime and aim for normal travellers to be affected as little as possible by the border control. Officers will be focused on cross-border crime involving explosives, weapons and drugs.”

There have been 13 explosions in and around Copenhagen since February, including the bombing in August of the Danish tax agency by what authorities described as “criminals who had crossed the border from Sweden”. Two Swedish nationals are in custody.

The double murder in June of two Swedish citizens in Copenhagen was “a showdown between feuding gangs from Sweden”, the Danish justice minister, Nick Hækkerup, said, adding that Denmark “cannot accept serious crime flowing over the border”.

Malmö, 25 miles from Copenhagen by the Øresund crossing, has been the scene of many of the gangland bombings and shootings that have recently struck Sweden. On Saturday a 15-year-old boy was shot dead in the city and another teenager critically wounded. Both were known to police.

Under increasing pressure to act, the Swedish government has announced a 34-point plan to combat the violence, including measures making it easier for police to search suspects’ homes and read encrypted phone messages.

EU rules allow temporary border controls to be reinstated within the passport-free Schengen zone for periods of up to six months, after which member states must apply to the European council for any further extension.

Sweden has had controls on visitors from Denmark since Europe’s 2015 migration crisis, and Denmark had operated checks on its border crossings with Germany since early 2016, extending them several times.