A Chinese research vessel has been identified in the waters of Indonesia with its tracking system turned off, authorities say, amid concerns in the region about China's maritime conduct.
Colonel Wisnu Pramandita, spokesman of Indonesia's maritime security agency known as Bakamla, said authorities suspected the vessel was conducting unauthorised activities in the Sunda Strait after its automatic identification system (AIS) had been switched off three times.
The Xiang Yang Hong 03 exited Indonesia's exclusive economic zone late on Wednesday.
Indonesian security officials have closely watched activities of Chinese vessels around the archipelago amid wider tensions in the region and concern about the country's militarisation and the conduct of its coastguard and fishing fleet.
The incident follows the recent discovery of an autonomous underwater vehicle (AUV) by a local fisherman off Indonesia's Sulawesi island last month, sparking concern about a potential security breach.
Analysts said the AUV may have been made in China.
The navy is still investigating its origins.
It was not immediately clear if there was a connection between the research vessel and the AUV, Bakamla's spokesman told Reuters.
The Xiang Yang Hong 03 during radio communication told Indonesia authorities its AIS had malfunctioned, Bakamla said.
The vessel was spotted during operations to recover the Sriwijaya Air jet that crashed into the Java Sea on Saturday with 62 people on board.
The Chinese embassy in Jakarta was not immediately available for comment on the vessel while a spokesman for Indonesia's foreign ministry said he was not aware of permission being granted for any maritime research activities.
The Indonesian archipelago straddles strategically important sea lanes used for trade, with its waters also home to rich fishing grounds and important energy reserves.