The mayor of Rio de Janeiro has criticised a Brazilian judge's decision to order visitors from the US to be fingerprinted and photographed.
US visitors faced new procedures on arrival in Brazil
Mayor Cesar Maia said the extra immigration checks would damage tourism - particularly in Rio.
He called the measures, introduced on Thursday, naive and reciprocal.
The decision by Judge Julier Sebastiao da Silva followed US plans to introduce tougher immigration checks on Brazilians entering the United States.
He made the order after a Brazilian Government office filed a complaint in a federal court over the new US immigration measures.
From 5 January, travellers from all countries which need a visa to enter the US will undergo the same checks.
"I consider the act absolutely brutal, threatening human rights, violating human dignity, xenophobic and worthy of the worst horrors committed by the Nazis," said Mr Sebastiao da Silva in the court order.
Police in Brazil said they began checking fingerprinting and photographing US visitors from Thursday.
A federal police spokesman said Mr Sebastiao da Silva's order could be overturned by Brazil's justice system if it was thought he had acted outside of his powers.
The US said it would watch closely the new Brazilian rules, but stressed
that it was the country's right to impose such requirements.
"Our consulates general in Sao Paulo and Rio de Janeiro are monitoring developments on this issue closely," said deputy US state department spokesman Adam Ereli.
But he added that the US had no plans to complain or even discuss the regulations with the Brazilian authorities.
"This is their sovereign right to do if they want to do it," he told reporters.
Mr Sebastiao da Silva's order was in response to Washington's new rules as part of increased anti-terrorism measures.
They aim to identify people who have violated immigration controls, have a criminal record or belong to groups that Washington has on its list of terrorist organisations.
An official from the US Department of Homeland Security said at least two of the 19 hijackers in the 11 September 2001 attacks could have been stopped if this security system had been in place.
It will not apply to citizens of 27 nations who do not require a visa to enter the US.