PAMPLONA: Using whistles to show their anger, hundreds protested in Pamplona on Tuesday after police said a woman had reported that she was raped during the Spanish bull-running festival and eight other women reported sexual assaults.

The alleged attack happened on Saturday in the northern Spanish city, Pamplona mayor Enrique Maya told reporters. Local police said they were investigating and that no arrests had yet been made.

"We are here because an (attack) has been committed, a rape," Tere Saez, from feminist group Lunes Lilas, told Reuters.

"We are here to tell this woman that we have not been able to prevent it but we are here, our hand is outstretched."

In a statement, the city council expressed its "total rejection and condemnation" of the alleged attack.

In 2016, the gang rape of an 18-year old woman at the bull-running festival caused public outrage and prompted calls to reform laws on sexual violence. Five men were later convicted and jailed.

The 2016 rape was known as the 'wolf pack' case because it was the name the men gave to their WhatsApp group on which they swapped images of the attack.

It led to a change in the law after the Spanish government approved a bill on June 6 last year to define all non-consensual sex as rape, part of a legislative overhaul that toughened penalties for sexual harassment and mandates more support systems for victims.