The General Workers' Union has forcefully condemned discriminatory language and hate speech.

In a statement slamming "divisive" comments, the country's biggest union said that it was against anything which fostered discrimination based on sex, gender, race, religion, ideology or anything else which encouraged division.

It emphasised that its statement should not be construed as an attack on freedom of expression, which it said was a right the union would defend with all its might.

READ: Former union chief likens protesters to prostitute

The GWU statement comes less than 24 hours after former union official Tony Zarb drew headlines and criticism for a Facebook post in which he likened women prostesting outside Castille to prostitutes.

"These [activists] went to the wrong place, because instead of Castille they should have gone to Strait Street... I'm convinced that if they feel cold they'll find someone to warm them up," Mr Zarb wrote.

Mr Zarb quit the GWU in 2015 and is no longer a part of union structures.

The GWU statement made no direct reference to Mr Zarb, and a union spokesman said that the hate speech condemnation was directed at discriminatory language wherever it came from.

They did, however, put distance between the union's position and Mr Zarb's words. 

"Mr Zarb left the GWU more than two years ago and has nothing to do with the union," they said.