MADRID (AP) — Spain’s postal service is feeling a backlash from its attempt to highlight racial inequality.

State-owned Correos España this week issued a set of four stamps in different skin-colored tones. The darker the stamp, the lower the price. The lightest color costs 1.60 euros ($1.95). The darkest one costs 0.70 euros ($0.85).

The postal service calls them “Equality Stamps” and introduced them on the anniversary of George Floyd being killed by a police officer in Minneapolis. It said the stamps “reflect an unfair and painful reality that shouldn’t be allowed” and that every letter or parcel sent with them would “send a message against racial inequality.”

The campaign was launched during European Diversity Month in collaboration with Spain’s national SOS Racism Federation, a nonprofit group, and featured a 60-second video with Spanish hip-hop star and activist El Chojín.

But while the goal of Correos España was to “shine a light on racial inequality and promote diversity, inclusion and equal rights,” critics are accusing the company of having a tin ear for racial issues and misreading the sentiment of Black people in Spain.

Antumi Toasijé, a historian who heads the government’s Council for the Elimination of Racial or Ethnic Discrimination, urged the postal service to stop selling the stamps.

“A campaign that outrages those it claims to defend is always a mistake,” he tweeted.

The postal service's initiative has divided Spanish anti-racism activists. While the national SOS Racism Federation backed it, the organization’s Madrid section poured scorn on the effort.

SOS Racismo Madrid said the campaign helps conceal the structural nature of racism and perpetuate the notion of Black inferiority.

Any racially aware person would have identified what was wrong with the campaign, it said, adding that the blunder proved the need for more racially aware people in decision-making positions at companies.

The campaign also received criticism on social media.

Correos España said Friday it would make no comment on the controversy.

This isn’t the first time the Spanish postal service has sought to make a statement on social issues. Last June, to coincide with LGBT Pride Month, it issued a special stamp and painted its delivery fans and mail boxes in rainbow colors.