Brent Central MP Dawn Butler claims she was a victim of racism in Parliament after a fellow MP "assumed she was a cleaner".
The black Labour MP said the incident took place in a members-only lift in Westminster and was one of "many incidents" she had experienced.
Speaking on Pienaar's Politics on BBC Five Live, when asked if she had experienced racism, she said: “Yes - God, there are so many incidents.
“There was a time when I was in the lift. It was a members’ lift that MPs use specially in cases (where) we have get to places quick[ly].
“I was in the lift and some other MP said: ‘This lift really isn’t for cleaners’.”
This is not the first time Ms Butler has spoken out about controversial issues.
In January, the MP came under fire for tweeting: "Cameron looks like a kid who's just done a poo said a friend. Yes it does feel like he’s sh***ing all over the working class doesn’t it’."
In 2008, she wrote how she was confronted by former Minister David Heatcote-Amory in a members-only bar, who asked if she was a member.
She wrote: "I said 'Yes I am, are you?'
"And he turned around and said to his colleague: 'They're letting anybody in nowadays.'
"This man could not equate the image he saw in front of him with that of an MP.
"It was quite upsetting for my team and so we had to take it further."
Mr Heathcoate-Amory dismissed the claims at the time, saying: "It is quite absurd... What she is actually objecting to is that I didn't recognise her as a new MP."
Just 6% of MPs are African-Caribbean or Asian, prompting Jeremy Corbyn to unveil a plan in 2015 to introduce more "working class background" MPs in a bid to create diversity.