A mother of three has been charged with assault by police for allegedly slapping her four-year-old son across the face at a shopping centre.

The woman's husband, who told Radio 6PR on Monday afternoon he wanted to be known as "John", said his wife struck their son on a shopping trip recently.

Sad child.

"She struck the four-year-old, after bitting an apple that hadn't been paid for by his mother," he said.

"She was pulled over in the car park after leaving the shopping centre after paying for the apple that was stolen effectively.