The Preah Sihanouk provincial court on Wednesday charged 16 crew members of a ship that allegedly entered Cambodian waters illegally.

The crew of the TM Courageous were charged for attempted smuggling and abusing territorial waters under the Immigration and Customs laws, said Lim Bun Heng, court spokesman.

The charges carry jail terms of three to six months and one month to one year, respectively.

Bun Heng said on Wednesday that the investigating judge was still questioning the suspects.

A National Police statement said the ship had violated U.N. sanctions banning ship-to-ship transfers to North Korean boats.

Border police found and seized the ship on Feb. 27 as it was anchored in Cambodian territorial waters between Koh Tang and Koh Poulo Wai in Preah Sihanouk province, the statement said. It had departed from Taiwan 12 days earlier.

The oil tanker bore the flag of Cambodia, though a shipping tracking website shows it has also flown the Cameroonian and St. Kitts and Nevis flags, including under a previous vessel name of “Sea Prima.”

National Police spokesman Chhay Kim Khoeun said the the arrests had been made to protect Cambodia’s borders.

“Our police forces will continue to strengthen and protect security for both the land and water borders of Cambodia, and we will cooperate with the authorities of neighbor countries for the safety and security of the people,” Kim Khoeun said.

Cambodia, which was once a close ally of Pyongyang, has sent back all 115 North Korean workers in the country as of December in order to comply with U.N. sanctions, the Khmer Times reported. Eleven companies and eight restaurants had been named in a government report as having been shut down, it said.