Widespread opposition.

The lawyer for a group of men convicted of the gang-rape of a young woman at a Spanish bull-running festival said he hopes to secure a reduction in one of his clients' sentences using a legal change governing penalties for sexual abuse.

The amendment, which took effect last month, has led to a series of sentence reductions in less notorious cases, drawing public outrage, accusations that it was poorly written and a spat between the government and judges.

At least 11 convicted sexual abusers have had their prison terms reduced and five men have been released from prison, according to Europa Press news agency.

Agustin Martinez, who represents five men known as the "Wolf Pack" who were convicted of the bull-running festival rape in 2019, told the Canal Sur radio station he intended to apply the new law to reduce the 15-year jail term of one of the men.

The new law classifies any non-consensual sex as rape but also set lighter minimum sentences for certain sexual crimes.

The General Council of the Judiciary, the ruling body for Spanish judges, said on Wednesday that the amendment obliged judges to retroactively apply the shortest sentence available to convicted felons.

Equality Minister Irene Montero suggested judges were not applying the law correctly in its "moment of transition", calling on the judicial system to "establish guidelines so that judges can correctly apply the law".

Cuca Gamarra, secretary general of the main opposition People's Party, called on Socialist Prime Minister Pedro Sanchez to revise the law, which he said left Spanish society less protected, and sack Montero, who was its chief sponsor.

The "Wolf Pack" case, dating to the 2016 San Fermin festival in Pamplona, stirred protests and calls for a change to the law after the defendants were initially convicted of the lesser crime of sexual abuse because, according to her lawyers, the 18-year-old victim did not resist out of fear.