The fire appears to have broken out in a building housing the "Teatre" and "Fonda Milagros" clubs in the city of Murcia in southeastern Spain.

"The fire spread from the upper parts of the two clubs, the Teatre disco and the Fonda Milagros disco... which originally were in the same building," said Diego Seral, spokesman for the national police.

Authorities do not yet know where exactly the fire started.

Police have established a list of 15 people missing after the blaze, but Seral said that it was not yet final and could contain names of some of the victims already found.

"The Murcia fire brigade... will continue to secure the building for the next few hours. It cannot be ruled out that another body may be located", the emergency service said shortly after 10:00 pm (2000 GMT).

They warned that there would be "no definitive toll until they have completed their work" scouring the rubble.

A man named Jairo who said he was the father of one of the victims told reporters that his 28-year-old daughter had been inside one of the clubs. He had had no news of her since she left a desperate voice mail at 6:06 am, he added.

"Mum, I love you, we're going to die, I love you mum," a young woman's voice could be heard crying on the recording while in the background people shout to turn the lights on.

Emergency services said on X, the platform formerly known as Twitter, that firefighters were continuing to work at the scene and had not ruled out "the possibility of finding more victims."

Jose Ballesta, mayor of Murcia, said the fire had broken out at around 6:00 am local time (0400 GMT) and had been "extremely serious".

Emergency workers had so far pulled out 13 bodies from the ruins, a task complicated by the risk of the building collapsing, he told journalists.

Three of the victims had been identified by their fingerprints. "The rest of the bodies will have to be identified by DNA."

Firefighters dispatched to the scene at 7:00 am were able to extinguish the fire by 8:00 am, he added.

Officials said four people, two women aged 22 and 25 years old and two men in their forties, were treated for smoke inhalation.

A police spokesperson said that a birthday party was being held at the club on Saturday night. Officers and firefighters were trying to find some of those who attended who were still unaccounted for.

"According to initial information, the fire broke out on the first floor of the nightclub, which has a ground floor and a first floor," Diego Seral, the national police spokesman told Radio Onda Regional de Murcia.

Video footage released by the city's firefighting brigade shows the firefighters holding a long hose approaching bright orange flames inside the venue, passing bar tables that still have drinks placed on top of them.

More than 40 firefighters and 12 emergency vehicles were attending the scene, authorities said.

Spain's king said he felt "pain and dismay" following "this tragic day in Murcia", and thanked rescue workers for their "exemplary work".

Prime Minister Pedro Sanchez voiced "solidarity with the victims and relatives of the tragic fire in a Murcia nightclub".

Spain's tennis superstar and this year's Wimbledon champion Carlos Alcaraz, who comes from Murcia, wrote on X that he was "very affected by the terrible news".

The city's mayor announced three days of mourning and set up a reception base for relatives of victims. The city's bars and restaurants will remain closed Sunday as a mark of respect to the victims, said Hoytu, the local hotel-restaurant association.

In 2017, 40 people were injured in a packed nightclub on Spain's holiday island of Tenerife when a floor collapsed.

The injured included people from countries including France, Britain, Romania and Belgium.

And in 1990, 43 people died in a fire at a nightclub in Spain's northeastern city of Zaragoza.

(AFP)