Two United Airlines planes collided while taxiing on the tarmac at San Francisco International Airport today, causing significant delays.

The pair of Boeing 777 clipped their wingtips while manoeuvring across the ground before they were due to take off.

Flight UA877, bound for Hong Kong, and Flight UA863, scheduled to fly to Sydney, were both affected and subsequently cancelled, as reported by aviation tracking service FlightAware.

Footage from the scene shows emergency responders inspecting the affected areas, assessing the situation, and ensuring safety following the incident.

The filmer, a passenger from one of the planes involved, said: 'I'm on UA877 and our plane just collided with another plane on the tarmac. So insane. I saw the other plane being towed out so close to ours as we were taxiing. I was holding my breath that we wouldn't hit.'

No injuries were reported, and an investigation is currently underway to determine the cause of the incident.