The warehouse was in a farm near Coria del Rio, a town of around 30,000 residents some 15 kilometres (nine miles) from the southern city of Seville, a spokeswoman for local emergency services said.

"The person who raised the alarm explained during the call that the roof had been blown off and the walls had been damaged," she added.

When emergency services arrived at the scene they found three people dead, she added.

The victims were between the ages of 40 and 61 who are believed to have been workers of the warehouse, a representative of Spain's central government in Seville, Francisco Toscano, told reporters at the scene.

Two of the dead were brothers, he added.

Preliminary evidence indicates the damage to the warehouse "seems to be from a tornado", Toscano said.

Spain's national weather office Aemet issued an alert for much of the southern region of Andalusia on Friday due to the risk from strong winds and heavy rainfall caused by Storm Nuria which was also affecting neighbouring Portugal.

It was the fifth storm to hit Spain since the beginning of March, which received 2.5 times the average amount of rainfall for the month this year, according to the weather office.

The storms have been blamed for a total of 10 deaths, including the three who died on Friday.