The Brazilian government has cancelled the visa of an American journalist who alleged that President Luis Inacio Lula da Silva has a drink problem.
Lula - here enjoying a glass of water - is angry about the claims
The Brazilian justice ministry said in a statement that Larry Rohter's report in the New York Times "offended the honour of the president".
It would be improper for Rohter to remain in the country, it added.
Mr da Silva, known as Lula, is also said to be considering legal action against the American newspaper.
Officials at the paper are standing by Rohter's report.
The head of Sao Paulo's foreign correspondents' association defended the reporter.
"It's a case of censorship and persecution by a democratic government," Veronica Goyzueta told Reuters news agency.
"It's from a government made up of people who suffered persecution," she added.
'Moderate social habits'
Sunday's article, headlined "Brazilian leader's tippling becomes national concern", appeared next to a picture of the president at a beer festival.
In the piece, the paper's Brazil correspondent questioned whether the president's performance was being affected by alcohol.
The president's spokesman called the report groundless, libellous and an example of the worst kind of journalism.
An official statement said Mr da Silva's social habits were moderate and no different from those of other Brazilians.
Brazil's ambassador to the United States was instructed to contact the paper's editor.
In parliament, leading senators called the piece an insult to Brazil.
Some politicians have alleged that Rohter made the story up while himself drinking beer on a beach in Rio de Janeiro.
The veteran journalist, who is married to a Brazilian, is thought to be travelling elsewhere in South America.
He will be contacted by the police on his return to Brazil.