Luis Rubiales delivers a speech during an extraordinary general assembly of the federation in Las Rozas de Madrid. File/AFP

Spanish football federation president Luis Rubiales has resigned following fierce criticism for kissing Jenni Hermoso on the lips at the Women's World Cup victory ceremony.

The already suspended Rubiales sent his resignation to the federation's interim president, he said in an open letter, and also explained his decision to eventually step down in a television interview.

"I'm going to (resign), yes, because I cannot continue my work," the 46-year-old told television show "Piers Morgan Uncensored".

"(Family and friends) say to me, 'Luis, you need to focus on your dignity and continue your life. If not you are going to damage people you love and the sport you love.'"

Rubiales sparked a worldwide backlash after forcibly kissing midfielder Hermoso during the medal ceremony following Spain's World Cup triumph in Sydney on August 20.

After he refused to resign, FIFA provisionally suspended him for 90 days, while Spanish public prosecutors have filed a lawsuit against him for alleged sexual assault and coercion.

Hermoso, 33, had filed a complaint at the National Court on Tuesday, formally accusing Rubiales of sexual assault.

In an open letter published by Rubiales on Sunday night, he said he had informed the federation he was also stepping down as a vice-president of European football governing body UEFA.

Luis Rubiales (right) hugs Aitana Bonmati on the podium at Stadium Australia in Sydney, Australia. File/AP

"After the swift suspension carried out by FIFA, plus the rest of the procedures opened against me, it is evident that I will not be able to return to my position," said Rubiales in the letter.

"Insisting on waiting and clinging to it is not going to contribute to anything positive, neither for the federation nor for Spanish football.

"Among other things, because there are powers that be that will prevent my return."

Rubiales, who insists the kiss was consensual, said he did not want Spanish football to be hurt by "such a disproportionate campaign" against him.

"I have faith in the truth and I will do everything in my power so that it prevails," he wrote.

Rubiales said his departure would contribute "stability" to the 2030 men's World Cup bid in which Spain are involved.

As the pressure ramped up in recent weeks on him to quit, Rubiales' mother Angeles Bejar went on a hunger strike in protest, locking herself in a church.

Agence France-Presse