The alert was raised at 10.50 a.m., the official said.

The helicopter was carrying five members of the Protection and Relief Intervention Group (GIPS), one of whom suffered slight injuries in the crash.

According to the civil defence website, 12 staff and five vehicles were sent to the site.

A red alert has been announced for most of Portugal through to midnight on Sunday, due to hot, dry conditions that raise the risk of forest fires.