A Spanish neo-Nazi has been seriously mauled by lions after jumping into their enclosure in a Barcelona zoo, the Mail Online reported on Monday.

Named by El Pais newspaper as Justo Jose, 45, the man was arrested last month in the Barcelona city center after draping swastika banners on the well-known Casa Mila building in an anti-abortion protest.

Zoo officials were unable to say whether the man entered the lion's enclosure as a demonstration.

"To enter the enclosure, you have to want to go in," said Barcelona fire chief Hector Carmona. "It couldn't have been an accident because the security system makes it impossible for a person to fall into the enclosure."

Dressed in military uniform, the man climbed over railings and began scaling one of the walls of the enclosure before one of the lions grabbed his leg and dragged him into the pit.

Fire fighters used hoses to keep the lions away from him for about 30 minutes before he could be rescued. He was taken to a city hospital where his condition was described as serious but not life-threatening.

Zoo keepers insisted the lions were merely trying to play with him, according to Spanish news outlet 20minutos. "The intention was not to kill him, they were just trying to play with him," said Ignasi Armengol, director of Barcelona Municipal Services.