The Brazilian Football Confederation (CBF) on Friday said questioning the integrity of the referee for Saturday's World Cup last-16 tie between Brazil and Chile was "primitive and immature".

Chile forward Alexis Sanchez and the president of the country's Football Association Sergio Jadue have expressed concern in the build-up to Saturday's game in Belo Horizonte that English referee Howard Webb might be influenced by the huge home support at the Mineirao.

"The only thing I fear is the refereeing," said Sanchez on Thursday when asked about the prospect of facing the tournament hosts.

However, when Brazil coach Luiz Felipe Scolari was asked to offer his thoughts during Friday's eve-of-game press conference, CBF press officer Rodrigo Paiva intervened.

"To talk about this subject is primitive and immature. Applying this kind of pressure is ridiculous," he said.

"Not only is it disrespectful towards FIFA, the referee and the Brazil team with their 100-year history of winning, but it is also disrespectful towards the people of Brazil."

Concerns that World Cup referees might favour the host country were first raised when Japanese official Yuichi Nishimura awarded Brazil a dubious penalty that helped them to a 3-1 win against Croatia in the competition's opening game.

Jadue called for a "top-level referee" to take charge of Saturday's game, and Webb has plenty of experience, having notably been the man in the middle for the 2010 World Cup final between Spain and the Netherlands in South Africa.