Five men cleared of gang raping a teenager in a case that provoked mass protests across Spain were granted on Thursday provisional release from prison, a judicial source said.

A court in the northern region of Navarra had cleared the men - who joked about the 2016 incident afterward on a Whatsapp group called "The Wolf Pack" - of rape and convicted them of the lesser crime of sexual abuse.

The incident happened at the annual San Fermin bull-running festival in Pamplona, the capital of Navarra, and followed concern over increased reports of sex attacks at the event as well as over the mistreatment of women in general in Spain.

It has also drawn international attention in the wake of the Harvey Weinstein scandal.

The judicial source said the five men would be released on bail by Friday, a move that led to renewed protests. Hundreds of demonstrators took to the streets in Pamplona, chanting "It's not abuse, it's rape."

All five, who include a former policeman and a former soldier, have to pay 6,000 euros ($6,960) in bail. The lawyer of four of the men, Agustin Martinez, told Spanish TV channel La Sexta he expected his defendants to put up their bail shortly.

The decision to release the men after almost two years in jail was based on a legal technicality. Their conviction is not yet final because prosecutors have appealed to a higher court, but under Spanish law people cannot usually be held for more than two years without a definitive sentence being handed down.

Feminist groups called for more demonstrations on Friday in Madrid against "patriarchal justice." Thousands took to the streets after the verdict was announced in April.

A spokesman for the court did not respond to requests for comment.