Indonesia has seized an Iranian tanker which was caught red-handed illegally transferring oil to a vessel from Panama, according to the coast guard.
The Iranian-flagged MT Horse and the Panamanian Freya were seized on Sunday in waters off Borneo and escorted to Batam Island for further investigation.
The coast guard said the vessels were detected at 5.30am, they were not flying any national flags, had switched off automatic I.D. systems and didn't respond to radio.
Spokesman Wisnu Pramandita said the ships were 'caught red-handed' transferring oil from Horse to Freya and that there was an oil spill around the receiving tanker.
Panamanian-flagged MT Freya (right) and Iranian-flagged MT Horse tankers anchored together in the Pontianak waters off the coast of Borneo on Sunday
The vessels were seized after they were 'caught red-handed' transferring oil to the Panamanian boat
The tankers are pictured after they were seized by the Indonesian coastguard on Sunday
He added that 61 crew members onboard the vessels were Iranian and Chinese nationals and had been detained.
The United States has imposed an economic strangle-hold on Iran since 2018 after it breached its nuclear commitments, hamstringing its oil exports to the world.
Experts estimate Tehran ships out less than 300,000 barrels of crude per day, compared to a peak of 2.8 million daily two years ago.
Iranian Foreign Ministry spokesman Saeed Khatibzadeh said today 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.
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.
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. Calls to the office went unanswered.
The oil tankers were seized off the tropical island of Borneo in South East Asia on Sunday morning
Iran has been accused of concealing the destination of its oil sales by disabling tracking systems on its tankers, making it difficult to assess how much crude Tehran exports as it seeks to counter U.S. sanctions.
In 2018, former President Donald Trump pulled Washington out of Iran's 2015 nuclear deal with six major powers and reimposed sanctions aimed at cutting Tehran's oil exports to zero.
Iran sent the MT Horse vessel to Venezuela last year to deliver 2.1 million barrels of Iranian condensate.
Over the past few months, MT Freya has delivered two crude oil cargoes totalling about 4 million barrels into Qingdao port on the east coast of China and northeast Yingkou port, said Emma Li, a senior crude analyst with Refinitiv.
The Qingdao cargo was declared as Upper Zakum crude produced in the United Arab Emirates, said Li, who tracks China-destined crude oil shipments.