Former foreign affairs minister Kevin Rudd has started damage control to head off a potential diplomatic row with China after a media storm over an alleged attack on two Chinese students in Sydney.

Police said six people, aged 14 to 18, robbed passengers on a train between Central and Rockdale about 12.30am on Monday.

Kevin Rudd ... mandarin-speaking MP. Credit:Matt Roberts

Officers were called to Rockdale station about 15 minutes later, where they arrested three men, two aged 18 and one 19, a 14-year-old boy and two girls, aged 16 and 17.

They were all charged with a number of robbery and assault offences.