Forest fires raging across Sweden as far north as the Arctic Circle have prompted authorities to ask for international assistance.

On Wednesday afternoon, 44 fires were burning from Lapland in the far north to the southern island of Gotland.

Hot weather and persistent drought are the main causes, and the national weather service has issued fire warnings for almost the entire country.

Many people have been evacuated from their homes in Sweden, while others have been told to shut off all ventilation to keep smoke outside.

Nine important public warnings have also been issued - a record number - as temperatures have hovered near or exceeded 30C for an extended period.

Sos Alarm, the emergency number operator in Sweden, said its services were stretched thin because of the fires.