RIO DE JANEIRO, Brazil (AP) _ For 6-year-old Carlos Rossi, a school exchange program in Florida offered a chance to polish his English and maybe even see Donald Duck.

But when the U.S. consulate denied him a visa, the mixed-race child became the subject of protests and discrimination charges, and a public relations nightmare for U.S. diplomats.

``The racism here is impossible to deny,'' Carlos' father, Luiz Carlos Rossi, who is white, said in a televised interview. He noted that the other 18 children in his son's program are white and were able to obtain visas.

The consulate, however, said Carlos' visa was rejected for a simple reason: The Rossis didn't present the needed documents and failed to persuade interviewers that the boy wouldn't stay in the United States illegally.

In the meantime, Brazilian newspapers have run with the story, turning it into front-page news.

``Consulate Must Explain Veto of Mulatto,'' read a headline Monday in Rio's Jornal do Brasil, adding that the refusal ``threatens to become a diplomatic incident.''

It didn't help that this is black pride week, and black rights groups quickly took up the banner. Ivanir dos Santos, head of the Marginal Peoples Representation Center, announced that he would seek the mediation of the Rev. Jesse Jackson, who is on a week-long visit to Brazil.

About half of Brazil's 155 million people are black or of mixed race. But racism, though often veiled, is widespread; few blacks hold prominent positions in government or industry, and they tend to be less affluent than whites.

Typically, children who take part in foreign exchange programs like Carlos' are white, as they are the ones who have enough money to study in private English programs.

Nevertheless, newspapers urged the Foreign Ministry to lodge a protest. The ministry said it couldn't interfere in the consulate's decision, but U.S. Ambassador Melvyn Levitsky promised to investigate.

The consulate has said it would reconsider Carlos' application if it offered better evidence that the boy wouldn't stay in the United States.

``They had to do more convincing. That's how the misunderstanding started,'' said the consulate's new information officer, Paul Kozelka, who arrived this week.

But the director of Carlos' English program, Ricardo Oliveira Lima, was quoted in O Globo newspaper as saying that the consulate has discriminated for years.

``The discrimination is clear,'' he said. ``For seven years we have maintained a cultural exchange program, sending groups of at least 10 students to the United States, and only those of mixed race have had their visas denied.''

On Tuesday, Lima was called to the U.S. consulate, and after a discussion with consular officers he signed a letter retracting charges of racism in Carlos' case.

``I signed the letter saying I couldn't prove anything,'' he told the Jornal do Brasil news agency. ``If I said that it was racism without proof, I could be sued.''