Boy slips between gap of Sydney train and platform in heart-stopping footage

This is the terrifying moment a young boy falls between a stationary train and the platform as his grandparent try desperately to signal for help.

The CCTV footage was captured at Cronulla train station in Sydney's south-east last year and shows the young boy attempting to board the train with what appears to be his sister and grandparents, reports the Daily Mail.

The family are shown approach the train and the grandmother enters with the young girl but just as the young boy and his grandfather are about to board disaster strikes.

The little boy misjudges the distance between the platform and the train and steps directly into the gap, his tiny frame fitting perfectly between the two.

The boy's grandfather watches on in horror as his grandson disappears down the gap and immediately begins to signal frantically to the train guard.

The man's wife also exits the train and attempts to get help for the boy.

The man then gets down on his hands and knees and reaches down to the boy and manages to pull him back out safely.

The man embraces the boy tightly before a Sydney Trains worker rushes over to check on the boys welfare and ask how the unfortunate mishap happened.

The boy appears to be uninjured although a little shaken from the ordeal.

Transport Minister Andrew Constance revealed 223 children fell beneath trains at Sydney stations last year, The Daily Telegraph reported.

'Our message is don't rush, hold your child's hand and please take care when you are at a busy station,' Mr Constance said.