(Bloomberg) -- A 26-year-old oil tanker that’s moving fuel for Russia drifted for two days in a busy shipping lane in the Indian Ocean, drawing the attention of industry watchers and maritime safety officials. 

It the latest stark reminder an environmental risks posed by a shadow fleet hauling Moscow’s petroleum around the world.

According to satellite tracking data, the Turba — a vessel known to be carrying Russian petroleum — is now moving at about 5 knots in the direction of Singapore. 

For about 48 hours before that, when it was roughly 200 miles (320 kilometers) west of Aceh in Indonesia, the ship’s navigation status was “not under command.” The designation, which means a ship is unable to maneuver on its own and therefore to keep out of the way of other traffic, is often because of mechanical or related failures.

Built in 1997 and sailing well past the age at which most tankers are scrapped, the Turba was near but not within Indonesia’s maritime borders when it drifted, according to the country’s naval service department.

Many tankers from the so-called dark fleet transport oil from Russia — and sometimes Iran and Venezuela — to China, sailing through the Straits of Malacca, the world’s busiest maritime chokepoint. 

The Mediterranean waters around Greece, where the Turba started its journey, are a common departure point, with cargo transfers taking place not far from that country’s coast. The switches create a degree of separation for those who want to buy the fuel at arm’s length.

The risk posed by such vessels, key to efforts to keep Russian and Iranian crude flowing, is not theoretical. In May, another 26-year-old oil tanker, the Pablo, exploded in the South China Sea.

Mystery Owners

Just like the Pablo, the Turba has mysterious ownership and has undergone relatively little inspection over the past several years.

It is flying the flag of Cameroon, a nation at the very bottom of a blacklist published by the Paris MOU, an international organization promoting safe shipping. 

In general, older ships that have been poorly maintained carry a greater safety risk. Obtaining the right spare parts for them can also be problematic.

In the past year, however, sanctions on Russia have prompted a surge in interest to buy and operate such vessels. 

The purchases are typically made by mystery entities seeking to avoid identification while transporting oil from sensitive regimes — a task that some larger and more reputable owners are increasingly unwilling to perform. 

--With assistance from Andrew Janes and Julian Lee.

(Updates with ship’s new navigation status in third paragraph.)

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