A Mexican political party has come under fire for bringing out topless women in body paint at a campaign event promoting women's rights ahead of weekend elections.

The four women appeared at Tuesday's event in Mexico City wearing white pants and turquoise paint over their breasts and stomachs -- the colors of the small New Alliance Party.

The word "free yourself" was painted in their backs, under a drawing of an unfastened bra. 

They stood alongside New Alliance leader Luis Castro, who smiled and applauded in front of a banner reading "For the Women and Girls of Mexico City." 

The party, an ally of the ruling Institutional Revolutionary Party in Congress, was closing its campaign for seats on a constitutional assembly for the capital.

The event was slammed by the federal government's National Women's Institute.

The institute said in a statement it "condemns and regrets the existence of political campaign strategies that denigrate women by exhibiting them as objects and repeating the sexism and stereotypes that encourage discrimination and violence."

The event was also criticized on social media, with Twitter users writing "misogynists," "very vulgar" or "how degrading."