Amanda Serrano has relinquished her WBC world title due to the fact the governing body will not sanction 12 three-minute rounds in women's boxing.

The Puerto Rican, 35, has been the undisputed featherweight champion since beating Erika Cruz last February, last retaining her crown against Danila Ramos in October.

Her victory over Ramos in Orlando was a historic clash as it was the first women's world title fight to be contested over 12 three-minute rounds since 2007, with Serrano winning by unanimous decision.

But the WBC are refusing to follow the same format used regularly in men's professional boxing, which has resulted in her vacating the strap.

Serrano wrote on Instagram: "Moving forward, if a sanctioning body doesn't want to give me and my fellow fighters the choice to fight the same as the men, then I will not be fighting for that sanctioning body.

"The WBC has refused to evolve the sport for equality. So I am relinquishing their title.

"Thank you to the sanctioning bodies who have evolved for equality!

"If you want to face me in the ring, you have a choice. I've made mine."

Men's title fights are held over 12 three-minute rounds, while women's bouts are usually contested in 10 two-minute rounds.

But two-weight undisputed world champion Katie Taylor has previously questioned whether there is enough "strength in depth" to switch to the men's format.

The Irish fighter said in November: "I don't know if women's boxing has the strength and depth to have three-minute rounds really. 

"For me, I really don't care whether it's a two or three-minute round. I spar three-minute rounds all the time. There's pros and cons to both really."