This is the moment a heroic cop saves a young child from choking after noticing two elderly people attempting to perform the Heimlich manoeuvre incorrectly.

Immigration police officer Ma Junlong was at the Erenhot City Government Service Centre in Inner Mongolia, China, on October 30, renewing his driver's licence when he suddenly heard a child crying.

An elderly person, apparently accompanying the toddler, said the child was choking on food and had attempted to help by flipping him over and patting his back, as shown in the dramatic footage.

Another onlooker tried to mimic the Heimlich manoeuvre, but Ma quickly realised that the elder was only holding the child upside down and repeatedly shaking and patting him - yet the obstruction was not coming out.

Recognising the situation's urgency, Ma took the child and applied the Heimlich manoeuvre, which he had learned during first aid training at work.

After about 20 seconds, the child spat out the milk tablet stuck in his throat.

Ma left after seeing that the child was safe, and later told local media: 'Being able to use my first aid knowledge to save a child makes me feel especially honoured and proud.'

The Heimlich manoeuvre, also known as abdominal thrusts, is a first-aid technique used to help someone choking due to a foreign object obstructing their airway. It is designed to expel the object by creating pressure in the abdomen.