LISBON, Sept. 4 (Xinhuanet) -- About 1,500 Portuguese firefighters battled Sunday seven forest fires in the central and northern parts of the country, which is facing the worst drought since 1945, the civil protection agency said.

    Backed by 381 vehicles and 28 aircraft, the firefighters battled in four of mainland Portugal's 18 administrative districts-- Braganca, Porto, Santarem and Viseu.

    As temperatures soared above 30 degrees Celsius across most of the country, three of Portugal's 18 districts faced a "maximum" wildfire risk, and another three a "very high" risk on Sunday, according to a daily risk assessment issued by the Forest Fire Prevention Agency.

    The wildfire risk has five levels: maximum, very high, high, moderate and reduced.

    Firefighters said the number of fires increased throughout the day as a result of strong winds and higher temperature.

    The blazes this year have killed at least 15 people, most of them firefighters, injured at least 16 firefighters as of Saturday and blackened nearly 240,000 hectares of land so far this year. Enditem