Police in Denmark, Sweden and Finland have stepped up security at airports and public places following the explosions in Brussels on Tuesday.
Danish police said they had increased patrols at Copenhagen airport and other key points in the city following the deadly explosions at Brussels airport and a metro station in the city.
"We are aware of what has happened in Brussels. Therefore you will see more police in the airport and at key points in Copenhagen," Danish police said on its official Twitter page.
Danish authorities have been on high alert since two people were killed in shooting attacks on a free speech event and a synagogue in Copenhagen in February last year.
In Norway, police officers in Oslo will carry weapons again for a temporary period, a police spokeswoman said. Officers were armed between November 2014 and February of this year due to a risk of attacks by Islamist militants. More police would also patrol the streets of the capital.
Police in Sweden said they had reinforced their presence at airports and taken increased security measures at other public places.
Finnish Interior Minister Petteri Orpo said on Twitter "Finnish security officials have increased monitoring at Helsinki-Vantaa airport".