Jennifer Lopez has hit back at an Instagram user who claimed the star's youthful looks are down to "tons" of Botox.

The 51-year-old responded to a post to clarify "for the 500 millionth time" that she has "never done Botox or any injectables or surgery".

Lopez had posted a video on the social media site, showing her glowing skin after saying she had used a face mask from her own J Lo Beauty range, which sparked the exchange.

"Honestly, I cannot even see a line on my face," she says in the clip, with the camera close-up to her skin. "It is glowy and gorgeous and tight and yummy."

She continues: "I feel like it took 10 years off my face."

The video has been viewed more than 7 million times, with many fans commenting on how Lopez achieves her youthful looks.

While many said it was down to her healthy lifestyle, others were not convinced.

"But can I just mention that brows and forehead doesn't move at all when you talk or try to express," one commenter said. "You definitely have Botox. And tons of it. And it's all good. Just saying."

Lopez responded by saying: "LOL thats just my face!!! ….For the 500 millionth time… I have never done Botox or any injectables or surgery!! Just sayin."

After encouraging fans to try her beauty range, the star added: "And here is another JLO Beauty secret: try spending your time being more positive, kind and uplifting of others don't spend your time trying to bring others down that will keep you youthful and beautiful too!!!

"Sending you love. #beautyfromtheinsideout #beautyhasnoexpirationdate."

One fan replied: "It's just envy that makes people disbelieve other people. Jennifer don't let that get you down. Stand over such comments. All the best!"