MADRID/BARCELONA (Reuters) - Wearing purple and raising their fists, hundreds of thousands of women took to the streets of Spanish cities on International Women’s Day on Friday calling for greater gender equality.

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The issue has become deeply divisive ahead of a national election on April 28. A new far-right party, Vox, which has called for a 2004 law on domestic violence against women to be scrapped, stands to win dozens of seats, according to opinion polls.

“We are unstoppable”, read one of the main banners in Madrid’s demonstration, where about 375,000 people, according to officials, completely packed a central avenue on a day marked by protests amid a national strike. Purple has in recent years been a signature color of women’s rights protesters.

“Everyone of us is fighting for a more democratic and egalitarian world,” said Ines Valverde, a 24-year-old psychologist protesting in Madrid, where people chanted “Madrid will be the tomb of machismo” and carrying placards saying: “All women can be what they want” and “Proud of my sisters”.

The march was peaceful and attracted people of all ages, including families with kids.

Elsewhere around Europe, campaigners for gender equality took to the streets to mark the day with protests and celebrations.

One of Spain’s largest unions, UGT, said an estimated 6 million people went on strike across the country for at least two hours to demand equal pay and rights for women.

In Barcelona, Spain’s second-largest city, about 200,000 people, according to local police, marched peacefully chanting and holding banners such as “The street is not a place to be afraid” and “I’m a feminist. I don’t hate men. I hate Vox and friends.”

The struggle for equal rights in Spain has also affected politics.

The conservative Partido Popular decided not to attend Friday’s demonstrations, arguing that they had been politicized by the left.

On the other hand, Prime Minister Pedro Sanchez’s Socialists have made gender equality a priority of their nine-month government and also of their re-election campaign.

Many of Sanchez’s ministers attended the marches. “Equality between men and women is the heart of democracy,”, said vice-president Carmen Calvo in Madrid, in a video released by her party, adding that the “Socialists will always fight that battle.”