In Brussels all metro stations were closed and public events were cancelled as the capital was warned of an "imminent threat" similar to the one that struck Paris last week.
Miriam Mannbro, spokeswoman at the Swedish Foreign office, said Swedes in Belgium are advised to use caution and stay abreast of what's happening.
"We are informing Swedish travelers in Belgium and especially Brussels to follow the local authorities recommendations which is to avoid crowds, for example concerts and public transportation," she said. "Local authorities also inform the public to be prepared for security checks."
Mannbro said the ministry was not telling citizens to cancel travel plans to Belgium but that they should be aware of the situation before leaving.
Jan Andersson, Swedish Radio News' correspondent in Brussels, said the capitol's streets were empty and Belgium media reported police found weapons during a search of a home