Brazil's reality TV show Big Brother is in for some real drama after it aired sexual assault of a contestant by another cast member.

The police are investigating the incident, a police spokeswoman of Rio de Janeiro told the Associated Press.

The contestants of the reality show are being questioned after contestant Daniel Echaniz was thrown out over suspicions of "gravely inadequate" behaviour, reports the Associated Press.

Thirty-one-year-old male model Echaniz was asked to leave the show after allegations of him having sex with another contestant, Monique Amin, surfaced. It is alleged that the model had sex with Amin when she had passed out.

The incident took place on the night of January 14 after a booze party. Blurry TV footage showed the two contestants in a bed and Amin without much physical movement.

"We analysed images that show a violation of the rules of the programme. Following careful study, the programme's management found that the behaviour of the participant ... was gravely inadequate," the Associated Press quoted Big Brother Brazil presenter Pedro Bial as saying on January 17.

Following the controversial airing of the programme, allegations are flying thick and fast that Echaniz was removed because of racism; Echaniz is of mixed race. A report in O Globo quotes Echaniz's mother as saying that her son is a victim of racism.

The incident has also generated a lot of debate on Twitter: whether Echaniz should be retained on the show and whether Amin was too drunk to know what was going on.

Big Brother show was first aired in Brazil in 2000 and is hugely popular.

The show originated in Britain and later TV channels from other countries produced their own versions. Participants in other Big Brother shows are often thrown out of the production for "objectionable" sexual behaviour; Echaniz's disqualification is the first such case on the Brazilian show.