Indonesian authorities on Sunday [Jan. 24] said they have seized an Iranian-flagged and a Panamanian vessel for illegal transfer of fuel between the two vessels and other marine violations.

Indonesia Coast Guard (IDNCG) in an Instagram post on Sunday morning said it had seized the two vessels in waters off Indonesia's West Kalimantan province for "violating the right of transit passage" according to its Archipelago Sea Lanes (ALKI) regulations and anchoring outside Alki limits.

According to the Associated Press, Wisnu Pramadita, a spokesman for the Indonesian Maritime Security Agency, said the Iranian-flagged MT Horse and the Panamanian-flagged MT Frea are suspected of a variety of violations, including not displaying national flags, illegal ship-to-ship transfer of fuel and spilling oil.

Iranian officials have not yet made any comments on the seizure of the oil tanker but the state-run television (IRIB) acknowledged the seizure of MT Horse without further details. 

Iran has been facing huge difficulties in selling crude oil under full US sanctions imposed in 2018 and 2019 after President Donald Trump withdrew from the 2015 nuclear agreement with Iran. To overcome the obstacles, Iranian vessels in several cases have reportedly transferred their crude oil cargos to other tankers in waters near Malaysia and Indonesia to cover up the source of the shipments. The shipments eventually went to China disguised as exports from Malaysia and other countries.

Still, Iran would face problems in receiving payment for any oil shipped to China as US has also imposed sanctions on Iran's international banking.

In August four oil tankers were stripped of their flags following investigations into allegations that they secretly transported millions of barrels of Iranian oil.

On January 4 Iran's Revolutionary Guards seized a South Korean tanker, MT Hankuk Chemi, and its 20 crew including two Indonesians near the Greater Tunb Island in the Persian Gulf. Iranian officials insist that the Koreas vessel was seized for "marine environment pollution."

The Indonesian Embassy in Tehran on January 6 in a verbal note to the Iranian Foreign Ministry protested the detention of its two nationals and asked for consular access to the detained sailors.