Estonian authorities said Saturday that they will not allow an oil tanker believed to belong to Russia’s “shadow fleet” to pursue its journey until it has resolved various legal and safety issues.

The Kiwala tanker was detained Friday in the Gulf of Finland in order to check its papers, which revealed that the boat is stateless. Two days earlier, the Estonian parliament passed legislation granting the country’s Defense Forces the authority to use force against vessels in the Baltic Sea if they are found to pose a threat to national security.

Kristjan Truu, director of the Maritime Department of the Transport Administration, said 40 problems have been detected with the boat, 23 of them having to do with documentation and the rest involving its seaworthiness.

“We cannot allow the ship to continue its voyage because maritime and environmental safety cannot be guaranteed,” he said.

Documents produced during the initial inspection indicated the Kiwala was sailing under the Djibouti flag, but the East African country quickly responded by saying it had de-registered the tanker.

The vessel is currently anchored in Muuga Bay and remains under surveillance by the Estonian Navy.

The Kiwala is under sanctions from Canada, the European Union, Switzerland and the United Kingdom and was on its way to the Russian port of Ust-Luga, Estonian officials said.

Security analysts say Russia is operating a “shadow fleet” of hundreds of vessels, seeking to dodge sanctions imposed on its oil exports over the war in Ukraine.

Estonian border guard head Veiko Kommusaar said the boat’s captain was Chinese, with most of the 24-member crew from either China or Mauritania. The Ukrainian sanctions-monitoring portal War & Sanctions noted that the Kiwala was previously commanded by a man named Sergei Kharchenko.

The vessel is owned by Tirad Shipping, a Mauritius-registered company whose fleet consists solely of the Kiwala. The tanker previously belonged to Turkish and Indian shipping firms.