"Fanzone is an important part of our website because it gives fans the chance to express their views," said Phil Townsend, Manchester United's director of communications.
"There is an explicit warning that the views contained in that part of the site are not necessarily those of Manchester United.
"But this is clearly an occasion where we got it wrong. We apologise for any offence that has been caused and have removed the offending items.
"We've put in place systems to try and ensure this does not happen again."