The Navy says it seized a ship loaded with pottery artifacts in waters near the Thousand Islands on Saturday.
This follows last week's seizure of four ships loaded with similar artifacts in the South China Sea and the arrest of two non-Indonesian nationals for allegedly looting ancient shipwrecks.
The Navy's Java, Sumatra and South China Sea commander, Brig. Gen. M. Jurianto, said that thousands of pieces of pottery, glassware and other artifacts were recovered from the ship, which he says was about to leave Indonesian waters.
"They were about to leave Indonesia to sell the treasure. We arrested 16 people, including the divers, the ship's crew members and the captain. We are now detaining them and keeping the ancient artifacts at our base in Tanjung Priok Port," he told The Jakarta Post on Sunday.
The suspects, all believed to be Indonesian nationals, would be handed over to prosecutors.
Jurianto said that archeologists had examined the pottery, and concluded that most pieces dated back to 16th and 17th centuries.
"The recovered items are worth billions of rupiah. We will hand them over to the prosecution service to be used as evidence in court, and, hopefully, they will be forfeit to the state afterwards," he said.
Jurianto said that last week the Navy had also detained four ships and arrested 26 people for illegally salvaging ancient artifacts from a shipwreck off the coast of West Kalimantan.
In the operation, he said the Navy had confiscated over 260 pieces of pottery and glassware taken from a sunken Chinese ship in the South China Sea off Pontianak last Wednesday.
AFP reported on Saturday that the pottery had been examined by archeologists in Pontianak, who dated most of the pieces back to China's Song dynasty (960-1297).
They were lying at depths of up to 30 meters and were recovered by traditional divers.
"We are still investigating whether the two seizures were connected with the cases ... in the Bangka-Belitung Islands and in Cirebon, which involved a number of foreigners," Jurianto said.
A German citizen, identified as Fred Dopperphol, and a French national, identified as Jeane Paul Blanc, were arrested by National Police last Wednesday in their home for taking part in an allegedly illegal salvage operation on a shipwreck located about 70 miles off the Cirebon coast in West Java.
They were charged as suspects and detained by the police, and now each face a maximum punishment of 10 years in prison if found guilty of violating the National Resources Conservation Law.
Both the French and German embassies maintain that their nationals had the necessary permits from the relevant ministries to conduct the salvage operation.
The embassies say that during the pair's arrest, which took place in their home in the middle of the night, they were not given the chance to produce the necessary documents, which were held by their employer.