Rio De Janeiro: Brazilian police are investigating claims that an alleged sexual assault was aired on the country's Big Brother reality TV show, a spokeswoman for Rio's police department said Tuesday.

Police inspector Antonio Ricardo L. Nunes said he questioned show participants a day after the wildly popular programme announced that contestant Daniel Echaniz was being thrown out over suspicions of "gravely inadequate" behaviour.

Nunes would provide no details on the questioning.

Echaniz, a 31-year-old male model, was booted off the show after allegations emerged that he had engaged in sexual behaviour with contestant Monique Amin after she'd passed out from drinking alcohol.

Leopard print sheets

The incident allegedly took place following a party on Saturday night. Grainy programme footage shows the two in a bed, the leopard print sheets moving as Amin lays inert.

Speaking on Monday night's show, Big Brother Brazil presenter Pedro Bial said: "We analysed images that show a violation of the rules of the programme".

"Following careful study, the program's management found that the behavior of the participant ... was gravely inadequate," he said. 

The grainy, black-and-white footage appeared on the pay-per-view version of the show, and a five-minute-long video excerpt is widely available on Brazilian websites.

The incident has been the subject of intense discussion, sparking questions about what exactly entails sexual assault.

It's a sticky topic in Brazil, where matters of sexuality remain fraught, despite the country's international reputation for sexual liberation.

Two opposing Twitter feeds have been created, one applauding Echaniz's removal and the other one advocating his return to the show.

A host of local celebrities have also chimed in on the Twitter debate, with several voicing suspicions that Amin was not really unconscious. Others have suggested the incident was her fault for drinking too much.

Echaniz's disqualification has also sparked murmurings about racism, as the dark-skinned male model is of mixed race, while Amin is white.

A report in the O Globo newspaper cites Echaniz's mother, Maria Aparecida Echaniz, as contending that "Daniel is the victim of racism.

"There have already been (such incidents on the show) and they didn't have such consequences," she is quoted as saying. While participants have been kicked off Big Brother productions in other countries for sexually questionable behaviour, this is the first disqualification on the Brazilian show.

Produced by Rede Globo channel, the Brazilian programme is in its 12th year.