In this photo taken on Jan 24, 2021, Panamanian-flagged MT Frea, left, and Iranian-flagged MT Horse tankers are seen anchored together in Pontianak waters off Borneo island, Indonesia. (PHOTO / AP)

DUBAI / JAKARTA - Iran has asked Indonesia to provide details about the seizure of an Iranian-flagged vessel, Iranian Foreign Ministry spokesman Saeed Khatibzadeh said on Monday, a day after Jakarta said it had seized Iran and Panama-flagged tankers in its waters.

Indonesia said on Sunday its coast guard had seized the Iranian-flagged MT Horse and the Panamanian-flagged MT Freya vessels over suspected illegal oil transfer in the country’s waters.

Khatibzadeh said that the seizure was over a “a technical issue and it happens in shipping field”.

“Our Ports Organisation and the ship owner company are looking to find the cause of the issue and resolve it,” Khatibzadeh told a televised weekly news conference.

Indonesia said on Sunday its coast guard had seized the Iranian-flagged MT Horse and the Panamanian-flagged MT Freya vessels over suspected illegal oil transfer in the country’s waters

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“The tankers, first detected at 5:30 am local time (2130 GMT on Jan. 23) concealed their identity by not showing their national flags, turning off automatic identification systems and did not respond to a radio call,” Wisnu said in a statement on Sunday.

Wisnu told Reuters on Monday that the ships were “caught red-handed” transferring oil from MT Horse to MT Freya and that there was an oil spill around the receiving tanker.

He added that 61 crew members onboard the vessels were Iranian and Chinese nationals and had been detained. Indonesia’s foreign and energy ministries did not immediately comment on the matter.

The International Maritime Organization requires vessels to use transponders for safety and transparency. Crews can turn off the devices if there is a danger of piracy or similar hazards. But transponders are often shut down to conceal a ship’s location during illicit activities.

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Both the supertankers, each capable of carrying 2 million barrels of oil, were last spotted earlier this month off Singapore, shipping data on Refinitiv Eikon showed.

Very Large Crude Carrier (VLCC) MT Horse, owned by the National Iranian Tanker Company (NITC), was almost fully loaded with oil while VLCC MT Freya, managed by Shanghai Future Ship Management Co, was empty, the data showed.

NITC was not immediately available for comment.

A search by Reuters on Chinese company directory found that the registered office address of Shanghai Future Ship Management Co came under another firm named Shanghai Chengda Ship Management. Several calls made to the office went unanswered.