Two Qantas planes were involved in a near-miss on the runway at Sydney Airport, prompting an urgent safety probe.

The Australian Transport Safety Bureau (ATSB) is investigating why a Qantas jet was allowed to cross the main runway as a QantasLink flight was landing on July 27. 

The Bureau described the incident as a 'breakdown of co-ordination'. 

'Air traffic control cleared the 737 on runway 25 to cross runway 34L while the Q400 was in the landing roll on runway 34L,' it said.

'ATC detected the conflict and advised both crews with the 737 stopping after the holding point.' 

The Daily Mail understands that both aircraft were acting on instructions from Airservices Australia air traffic controllers. 

A Qantas spokesman told Daily Mail 'both Qantas aircraft were cleared to proceed following instructions from air traffic control'.

'We will support the ATSB in the investigation,' he said. 

Air traffic controllers and pilots will be interviewed, while investigators will also  retrieve recorded data and other relevant information. 

The investigation is expected to be completed by the end of the year. 

The Daily Mail has contacted Air Services Australia for comment.

Source: Daily Mail