Dozens of people have been injured after a rogue firework set off a huge explosion in a church bell tower in Elche, Spain during summer festivities.

Streams of sparks and burning material landed on people gathered below for a town festival.

A spokeswoman for Elche town hall said the church fireworks were covered by a protective blanket and in a pack designed to shoot mini-rockets some 300 metres into the air before exploding.

But the firework fired from elsewhere landed on the pack, igniting the fuses minutes before the scheduled midnight launch on Monday.

She said three firework operators were hospitalised for serious burns while 25 people were treated for minor injuries.

The Mayor of Elche, Mercedes Alonso, was jeered by the crowds as she left the event.