The former S Club 7 singer, who has two children ,Minnie Blossom, 18 months, and four-year-old Amelia, reportedly parked in north London then walked to the shops, leaving her children for 10 minutes, claim the Mail Online.
An onlooker at the scene told the Mirror: "At first I didn’t realise they were in the car on their own or how young one of them was but when I did it was quite shocking.
"I suppose I think about the worst-case scenario but what if they took off the handbrake or managed to get out of the car? Or if someone managed to get in?"
Photos taken by paparazzi show Stevens shutting the car door and walking away with her children left inside.
While she was gone, pictures were taken of her eldest daughter Amelia sat in the front seat on her own, with her sister in the back.
Despite the negative opinions voiced in the Mail and Mirror, on Twitter the majority of people have come out in the star's defence.
Jo Frost, also known as Supernanny, waded in on the debate. She tweeted: "I'm sure @MsRachelStevens is now aware that her parenting choice was not a smart one but... truly so fed up with celebs being publicly shamed."
Other parents agreed with Frost, arguing it was a simple mistake - and one that many parents have made.
The law regarding leaving your child on their own holds that it is only an offence "if it places the child at risk.
On the Government's website itstates: "The law doesn’t say an age when you can leave a child on their own, but it’s an offence to leave a child alone if it places them at risk.
"Use your judgement on how mature your child is before you decide to leave them alone, e.g at home or in a car."
The National Society for the Prevention of Cruelty to Children (NSPCC) states: "Children under 12 are rarely mature enough to be left alone for a long period of time.
"Children under 16 shouldn’t be left alone overnight. Babies, toddlers and very young children should never be left alone."
What do you think?