The extreme heat engulfing regions of southern Spain claimed its second mortal victim when a 78-year-old man fell unconscious while tending to his farmland in Murcia and died in hospital soon after, local health services said Friday.

It was the second death attributed to the heatwave currently scorching the Iberian Peninsula after a 48-year-old construction worker succumbed to severe heatstroke Tuesday.

He had been taken ill the previous day while working at a construction site that was also located in the southeastern Murcia province. 

Weather warnings for extremely high temperatures are in place across the majority of the Iberian Peninsula, especially in central and southwestern provinces, where temperatures could soar above 40C (104F), while in Murcia the mercury was forecast to hit 37C. 

Spain's meteorological agency Aemet issued red alerts for high temperatures in the areas of Extremadura and Galicia bordering Portugal, with temperatures expected to hit 45C. 

Four forest fires broke out in Extremadura but firefighters were able to contain the flames.