Edward Snowden, the former US intelligence contractor turned whistleblower, has said he has requested asylum in Brazil, in an interview with journalists from the country.

Appearing on Brazil's Globo TV channel on Sunday, Snowden said he would not exchange information in return for asylum.

"I already sent a petition to the Brazilian government requesting asylum. So if they chose to offer it I would definitely accept," Snowden said.

Brazil's foreign ministry said it had not received any formal request for asylum, the Reuters news agency reported.

The former operative for the National Security Agency (NSA) was charged by the US last year over allegations of theft of government property and disseminating classified material to unauthorised people.

US officials have demanded Snowden returns home to face the charges from his current residence in Moscow, where he claimed asylum after leaking documents unveiling the extent of NSA spying in 2013.

Among the information leaked was evidence that the NSA had monitored Brazilian President Dilma Rousseff's email and mobile phone.

Dismissing suggestions he would supply Brazil with intelligence, Snowden said asylum would have to be "granted on humanitarian grounds", the Reuters news agency reported.

Brazil is currently home to Glen Greenwald, a former journalist at the UK's Guardian newspaper, who helped Snowden leak the documents.

Last year, Snowden made requests to a number of countries, including Brazil, for asylum.

The revelations of NSA spying damaged relations between the US and Brazil, prompting Rousseff to cancel a state visit to Washington in October.

The spying also led to Rousseff to become a global advocate for curbs on Internet surveillance.

Snowden has stated that he is not under the control of Russia's government and has given Moscow no intelligence documents after nearly a year of asylum there. He said that living in Russia is better than prison.

Snowden, who fled to Hong Kong and then Moscow last year, is believed to have accessed about 1.5 million secret documents, US officials have said, although how many he actually took is unclear.