Fianna Fail TD Jack Chambers has criticised RTE for its decision to allow McDonald's to sponsor the Big Big Movie.
The flagship weekend slot, a favourite for families after the Six One News on Saturdays, is now supported by the fast food giant.
Mr Chambers said the national broadcaster could be in breach of its standards, adding that the sponsorship could encourage unhealthy eating habits among children.
"It is remarkable that RTE are allowing McDonald's to sponsor this slot, despite the ban on high-fat, salt and sugary foods during children's programming," he said.
"As their own website details, this programme slot has a quarter-of-a-million viewers including a 31pc average share of viewing for kids.
"Sponsorship can reach 85pc of households with children.
"Evidence is clear that the advertising of junk food adversely influences children's preferences and heavily contributes to childhood obesity.
"Our national broadcaster should be doing more to protect Irish children from any exposure to the advertising of unhealthy food.
"RTE's clear breach of public responsibility underscores the need for a blanket ban on advertising of junk food during the watershed hours of 6am to 9pm."
A spokesman for RTE said it was fully compliant with national broadcasting codes.
He said the Big Big Movie slot "is scheduled for family viewing on a Saturday evening when children can enjoy a popular movie in the company of parents or guardians".
The spokesman added that RTE was a dual-funded organisation and was legally obliged to supplement the licence fee with commercial income from sponsorship.
He added that the income from such sponsorship goes towards health- focused programmes such as Operation Transfor- mation and Ireland's Fittest Family.