Chinese warships have carried out naval drills in Australia's maritime backyard for the third time in three years in a move that experts say strengthens the case for greater co-operation with Indonesia.

China's state media have reported that two missile destroyers and a supply ship conducted combat exercises during a 25-day voyage that took them close to Australia's Christmas Island.

China's missile destroyer Haikou, which took part in the exercises, in 2014. Credit:Zheng Wenhao

The People's Liberation Army Navy made major headlines in early 2014 when they carried out similar drills in the eastern Indian Ocean close to Australian territory for the first time. This was followed by anti-piracy exercises close to Christmas Island in May last year.

It is understood the Australia Defence Force monitored the latest Chinese activities and the ships' passage between Indonesian Java and Christmas Island.