Indonesian authorities said two oil tankers - the Iranian-flagged MT Horse and Panamanian-flagged MT Freya - were released after being detained for four months for illegally transporting oil in Indonesian waters, the Associated Press reported.

The two ships were released on Friday and their captains were allowed to leave, despite being sentenced to a year in prison on Tuesday for violating shipping channel rules, said Wisnu Pramandita, a spokesman for Indonesia’s Maritime Security Agency.

According to Pramandita, MT Freya was also fined 2 billion rupees (almost $ 140,000) for an oil spill at sea. Iran has been selling oil on the black market since President Donald Trump imposed sanctions in 2018 and threatened to punish countries that bought Iranian oil. Iranian oil tankers turn off their tracking equipment, hiding the purpose of their voyage.

MT Horse and MT Freya were detained at the end of January, along with 36 Iranian and 25 Chinese crew members. A few days later, the Chinese government called on Indonesia to treat the Chinese sailors fairly, but gave no indication of what their oil tanker was doing when it was found carrying fuel from an Iranian ship at sea.