Emma Dent Coad, the MP for Kensington, claimed Prince Philip had been “mucking about for years" and has “not been a faithful husband” during a pro-republican fringe meeting at the Labour Party conference in Brighton.
Ms Dent Coad, who counts the Duke and Duchess of Cambridge and Prince Harry among her constituents, mocked Prince Harry for his abilities as a helicopter pilot before confessing her criticisms may have been incorrect.
According to The Sun, the 62-year-old told party activists at a “Reigning in The Monarchy” event: "Harry can't actually fly a helicopter."
She added: "He tried to pass the helicopter exam about four times and he couldn't get through it at all so he always goes for the co-pilot. So he just sits there going 'vroom vroom'."
The MP, who led Labour to win Kensington for the first time in history, also branded Prince Harry and his brother "not very bright".
She said: "Just let them drift away, be playboys or whatever."
The politician argued it was “disgusting” the Duchess of Cambridge had bought sweaters costing £150, saying: “That’s a food bill for a family of four.”
The politician, who has been commended for her response to the Grenfell tower tragedy, was criticised by fellow Labour MP John Woodcock for the remarks about the Prince.
"The highly inaccurate comments reportedly made by one of our colleagues, which disparage Prince Harry's military service, in no way reflect the views of my party,” he wrote on Twitter.
"Like everyone who put themselves in harm's way to keep us safe, His Royal Highness deserves nothing but praise and respect for his service in the armed forces.
"In addition to his tours of duty in Afghanistan, Prince Harry inspires so many by the way he champions injured, ill and wounded servicemen and women through the Invictus Games which he founded. I am really sorry that this has happened."
When pressed about her comments about Prince Philip and the Queen, Ms Dent Coad told the Evening Standard: “Oh no, shock horror. I’m not going to respond to that, everyone knows what’s going on... I don’t want to get into the detail of it because it’s got out of hand.”
She added: “I was talking about whether taxpayers should fund the royal family.
“I was just poking fun. But we need a proper debate about the royal family. It’s about taxpayer funding. Why are taxpayers funding them? Why can’t I disagree? It seems like we are not allowed to have an opinion.
"I’m being called everything under the sun this morning, getting all sorts of vile abuse. This has opened the gates to hell.”
She confessed she may have been incorrect about Prince Harry’s military record.
Ms Dent Coad won the west London borough of Kensington, which has been Conservative since it was created in 1997, by just 20 votes during the snap election. During one of the biggest shocks of the night, Conservative MP Victoria Borwick saw her majority of over 7,000 overturned in the affluent central London area.
A representative for the royal family refused to comment on Ms Dent Coad's initial comments at the Labour Party conference.