A 10-month-old boy was rescued by a local cleaner when his stroller rolled into a river.

Smartphone footage showed the stroller with the child inside sliding down aslope and plunging into the water in the city of Tongxiang in Zhejiang, China, on January 25.

Just seconds later, river cleaner Xu Shuigen, 70, paddled towards the child in an attempt to save him, as terrified witnesses watched from the bank.

Shuigen then used a fishing net to save the boy, before he returned him to his grandmother.

Chinese media reported that the incident happened when the elderly lady stopped at a local convenience store and left the stroller unattended.

Following the successful rescue operation, the boy's family thanked Xu Shuigen for his heroic act.

Xu said: 'Saving people comes from instinct. Whether it is an old man or a child, if you see someone falling into the river, you must save them.'