Portuguese television news reported that the High Council for the Media plans to prosecute TVI and SIC.
TVI faces a heavy fine for its broadcast of sex scenes in Big Brother, but SIC could be liable for criminal prosecution for invading the right to privacy on its show O Bar da TV.
The head of the media watchdog, Artur Portela, said that Big Brother showed "excessive" sex scenes without appropriate warning.
He said the O Bar da TV offence was graver in that the programme "used" a confrontation between a contestant and her family in a way that "threatened the rights and interests of the contestant and her family."
The competitors on O Bar da TV live in a Lisbon apartment next to their only source of income - a bar.
The bar is only open to the public from Wednesday to Saturday, but what goes on in the apartment is broadcast on the internet 24 hours a day via 36 cameras.
'Debasement'
The High Council for the Media was forced to take action after SIC broadcast an emotional conversation between a competitor and her parents, who wanted her to leave the show.
Her parents were distressed by the previous day's broadcast in which the contestants passed around a vibrator and condoms and also by scenes of contestants showering naked.
The broadcast took place against the wishes of the young woman.
Two government ministers wrote to the authority asking it to take action on what they said was "a clear debasement" of the right to privacy.
One Roman Catholic bishop told a daily newspaper he was "shocked" that people were "selling their souls".
Legal, family rights groups and media figures have also criticised the show - with the daily paper Publico describing the show as "the most vile spectacle" ever on Portuguese television.
The 12 contestants on O Bar da TV are to be whittled down by a public voting system over three months and the eventual winner will collect 20 million Portuguese escudos (£61,495).
SIC used to be Portugal's leading television channel and is now engaged in a ratings war with the country's other private channel, TV1, is drawing record audiences with its reality show Big Brother - which has been a hit across Europe.