The trial of a security gate in a Woolworths in Sydney has left customers concerned for their safety, with some saying the series of low-height bars have “hit” children in the arms, legs and face.

Maria, who was shopping with her two children at Woolworths in Bass Hill in south-west Sydney on Wednesday, told Guardian Australia that she noticed the new entrance “straight away”.

“The level that they’ve put it at, is the level of the kids in the pram,” said Maria, who asked that her surname not be published.

“If you wanted to enter without hitting your child, you’d have to go in backwards.”

Woolworths is trialling the new anti-theft entry gates in six stores, including Sydney’s Bass Hill and Camberwell in Melbourne’s east.

Maria said she was surprised that the gate wasn’t temporary, and told Guardian Australia that many parents with similar experiences had complained to Woolworths, asking them to change it back.

The gates contain two sets of bars that can only be pushed in one direction. Maria said she was particularly worried about children grabbing the bars, which may spring backwards into them. Describing her one-year-old, Maria said that obviously he’s going to play with them.

Susan, who asked that her surname not be published, has lived in Bass Hill for 50 years. She was caught off guard by the change and like many others felt uncomfortable.

“I thought, I’m going to get caught in there,” she said. “I’m going to get stuck.”

Prior to the new gates’ installation, entry to the Bass Hill Woolworths was via a sliding door.

Customers in Bass Hill first noticed this change last week, but the first store to introduce this new entry was in Camberwell, Victoria, where the gates have been in place since late last year.

There has been significant backlash to the gates online. One Reddit post with more than 5,000 upvotes said: “These spring back and are at a toddler’s face height”; another with 2,900 upvotes said: “these gates make you feel like livestock”, while a third with 2,000 upvotes said: “I wonder how people with disabilities are going to get through these security gates.”

When Guardian Australia described Maria’s experience to Woolworths, a Woolworths spokesperson expressed concern and stated that they will be reviewing feedback as they assess the trial.

Woolworths is not the only retailer to introduce new preventative measures in response to rising retail theft. IGA, Spotlight and Drakes are using similar anti-theft gates in some stores.

The Woolworths spokesperson said that theft is one of the main drivers of violence and aggression towards their team members.

The supermarket giant is scheduled to enter legal proceedings with the Australian Competition and Consumer Commission defending their alleged pricing practices later in the year. Woolworths recently reported a 16% increase in profits over the past six months, up from $739m to $859m.

Most of the eight customers Guardian Australia spoke with at Bass Hill understood that the gates were changed to prevent theft, with one customer acknowledging that the entrance would “no longer be a run-away gate”. However, they felt that the tradeoff of convenience was not worth the additional security.

“It’s just quite annoying,” said Susan.