Officials have defended their move to confiscate an elderly hawker's roasted chestnuts trolley, after a video went viral online showing the woman on the ground and crying while surrounded by police officers.

The woman, who is in her 90s, reportedly asked a man she knows to look after her licensed trolley near Cheung Sha Wan MTR Station on Monday evening while she went to the toilet.

The man was arrested on suspicion of illegal hawking and the trolley was seized.

In a statement, the Food and Environmental Hygiene Department (FEHD) said in general, it is lenient when it comes to enforcement action.

"Because that spot is a main access that's very busy, FEHD officers gave a warning to the hawker and dispersed them, but didn't take enforcement action," the department said in response to media enquiries.

"An hour later, officers arrived at the scene again to investigate, and found that a man around 30 years old was operating the food stall," it said, adding that the woman only arrived around 30 minutes after police arrested the man.

The statement did not say if or when the woman might get her trolley back.