Hundreds of firefighters continued battling major wildfires in Portugal and Greece on Sunday, while authorities in northern Greece warned residents to stay indoors because of toxic smoke from a burning recycling plant.

In Portugal, more than 1,200 firefighters, supported by nearly 400 vehicles and 15 aircraft, were trying to contain a wildfire in the central Vouzela region that has been burning since Thursday. According to the European Union's Copernicus satellite monitoring agency, the fire had scorched about 12,000 hectares by Sunday.

Fast-moving wildfire forces evacuations near Greece's Thessaloniki

The European Union's Civil Protection and Humanitarian Aid department said Spain sent 120 firefighters and 45 vehicles to Portugal on Friday, while Italy and Spain also deployed three firefighting aircraft to assist.

In Greece, a wildfire that reached a recycling plant near the Thessaloniki suburb of Oraiokastro on Saturday evening forced evacuation alerts for three suburbs and a facility housing 157 people with special needs. Strong winds spread the flames, prompting the deployment of about 160 firefighters overnight until water-dropping aircraft joined the operation at daybreak.

Authorities advised residents in parts of Thessaloniki to remain indoors with windows and doors closed because of toxic smoke.

Mayor Pandelis Tsakiris said several homes and businesses were damaged. Police arrested a 76-year-old man on suspicion of accidentally starting the fire with sparks from his vehicle. Fire officials said about 85% of Greece's wildfires are caused by negligence, despite increasing use of satellite technology to detect fires.