A young boy is in a critical but stable condition after his heart stopped when he was struck by lightning on a beach near Wollongong on Australia Day.

NSW Ambulance chief inspector Terry Morrow said the boy was believed to be in the water at the time of the strike, which caused his heart to go into cardiac arrest and his breathing to stop.

The boy also suffered burns to his chest in the incident, Insp Morrow told Seven’s Sunrise program on Friday.

Surf lifesavers patrolling nearby commenced CPR on the nine-year-old with the help of a doctor who was on the beach with her family at the time.

Ambulance crews and police responded shortly after and paramedics took over resuscitation efforts.

They were able to re-establish the boy’s heartbeat and breathing before transferring him by road to Westmead Children’s Hospital, where he remained in a critical but stable condition on Friday.

A helicopter was dispatched from Albion Park with a doctor and intensive care paramedic who assisted in stabilising the boy.

The boy was unable to be transferred to hospital by helicopter due to the ongoing electrical storm, Insp Morrow added.

– AAP