At least 13 people have died in a fire that engulfed three nightclubs in the south-eastern Spanish city of Murcia.

The blaze broke out in the Fonda Milagros nightclub - known as La Fonda - early on Sunday morning.

It then spread to neighbouring clubs as patrons rushed to escape the packed dancefloors, police said.

Local media reported that family members celebrating a birthday were among the dead.

One of the the birthday party attendees - who was at the club with his cousins and aunt - said he returned home during the chaos, only to be told that one of his cousins had not left, La Verdad de Murcia newspaper reported.It is not clear if the cousin was among those confirmed dead.

Police have confirmed that all of those who died were at La Fonda, but added 14 people were still unaccounted for. They warned the number of deaths would probably rise.

The club is located in the Atalayas area in Murcia, and the fire is believed to have started at around 06:00 (04:00 GMT).

Nearly 15 hours on, it is still not clear what caused it. But Murcia's Mayor Jose Ballesta told reporters earlier in the day that the fire had broken out on the first floor of the club.

Diego Seral, of the national police, said the roof of La Fonda had collapsed, which was making it challenging to locate victims and work out what had happened.