Facebook has come under fire for allegedly failing to remove sexualised images of children from its site.
Damian Collins, chairman of the Culture, Media and Sport Committee, said he had "grave doubts" about the social media giant's ability to moderate content.
His comments came after the BBC said it used Facebook's "report button" to flag up 100 photos on the website, but 82 were not removed.
Instead, an automated response was provided which said the photos did not breach "community standards".
The images included under-16s in sexualised poses, pages aimed at paedophiles and an image which appeared to be taken from a child abuse video.
Among the items not permitted under Facebook's community standards is "sexually suggestive content".
When examples of the images were sent to Facebook, the company instead reported the journalists to police for sharing the pictures, the broadcaster claimed.
Mr Collins said: "I find it very disturbing, I find that content unacceptable.
"I think it raises the question of how can users make effective complaints to Facebook about content that is disturbing, shouldn't be on the site, and have confidence that that will be acted upon."
Anne Longfield, the Children's Commissioner for England, said she was "very disappointed" by the revelations.
A Facebook spokesman said: "We have carefully reviewed the content referred to us and have now removed all items that were illegal or against our standards.
"This content is no longer on our platform. We take this matter extremely seriously and we continue to improve our reporting and take-down measures.
"It is against the law for anyone to distribute images of child exploitation.
"When the BBC sent us such images we followed our industry's standard practice and reported them to Ceop [Child Exploitation & Online Protection Centre].
"We also reported the child exploitation images that had been shared on our own platform. This matter is now in the hands of the authorities."
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