A woman holds a placard as demonstrators gather in the centre of Madrid, Spain

Video. Watch: Thousands demonstrate in Madrid to condemn sexism in football

Spanish prosecutors said they have opened a preliminary investigation into Rubiales' forcible kiss on grounds it could constitute a crime of "sexual assault".

Spanish prosecutors said they have opened a preliminary investigation into Rubiales' forcible kiss on grounds it could constitute a crime of "sexual assault".

Under Spanish law, sexual assault covers a wide array of crimes from online abuse and groping to rape, each with different penalties.