Around 100 people were evacuated from the terminal and incoming flights were redirected to Arlanda’s Terminal 5.

Although the source of the smell of smoke has not been detected, rescue services have deemed it safe to reopen Terminal.

“Now it’s the technicians’ job to look in the ventilation room,” rescue team leader Magnus Gärtner told news agency TT.

Police were first called when people started smelling smoke in the terminal.

“It was spread through the ventilation system,” said police spokesman Björn Engström.

Fire fighters from Arlanda, as well as from nearby Väsby and Märsta, arrived on the scene but failed to locate any flames.

The incident has had “a minimal effect on traffic” said Swedish airport authority LFV Group spokesperson Jan Lindqvist to TT, adding that the smell of smoke came after the morning rush hour.

In addition to incoming flights, two outgoing flights – one to Las Palmas and one to Copenhagen – were also been moved to Terminal 5.

Lindqvist explained it may take time for crews to find the source of the fumes.

“It can be tough for emergency services because the smell of smoke may have traveled a long way through the ventilation system,” he said.