• The move to target these assets comes as the U.S. Justice Department announced a new task force that will help enforce sweeping sanctions against Russian oligarchs.
• French authorities seized a massive yacht they say is linked to Igor Sechin.
• Russian billionaire and business tycoon Alisher Usmanov's superyacht Dilbar was restricted from leaving its anchorage by German authorities on Thursday, according to an official with knowledge of the matter.

At least two superyachts owned by Russian oligarchs have been seized by authorities in the European Union after the executives were sanctioned following their country's invasion of Ukraine.

Russian billionaire and business tycoon Alisher Usmanov's superyacht Dilbar was restricted from leaving its anchorage by German authorities on Thursday, according to an official with knowledge of the matter.

The official, speaking on the condition of anonymity, said the yacht has not been physically seized but rather is not allowed to move from its current location in the German port city of Hamburg. The person added that more measures will be taken later.

The extraordinary yacht, named after Usmanov's mother, extends over 500 feet and is equipped with the largest indoor swimming pool ever installed on a private vessel. The Department of Treasury estimates that the current value of Usmanov's yacht is approximately $735 million.

A Treasury official referred CNBC's inquires for an update on motor yacht Dilbar to German authorities. The official, speaking on the condition of anonymity, said any action taken by German authorities would not involve transferring the vessel to the United States under Treasury's Office of Foreign Assets Control, or OFAC, sanctions.

Usmanov and his superyacht entered U.S. crosshairs on Thursday when the Biden administration announced additional sanctions on Russian elites with Kremlin ties.

The Treasury Department wrote in a release that Usmanov is close to Russian President Vladimir Putin and that his "Kremlin ties enrich him and enable his luxurious lifestyle."

The new U.S. sanctions listing Usmanov's yacht as blocked property effectively means that any transactions related to the yacht, including maintenance, the hiring of crew, payment of docking fees conducted with U.S. persons or in U.S. dollars are prohibited.

French authorities seized a massive yacht they say is linked to Igor Sechin, a Russian billionaire who is CEO of state oil company Rosneft. He previously served as Russia's deputy prime minister within Putin's government. Forbes reported that Sechin is known in Russian business circles as "Darth Vader."

Sechin was previously targeted with sanctions by the EU after the invasion of Ukraine.

The Lady M, a yacht owned by Russia's wealthiest oligarch, was also seized in Italy.

A media advisor to Italian Prime Minister Mario Draghi confirmed in a tweet that the superyacht known to be the property of sanctioned billionaire Alexei Mordashov was seized in Imperia.

Video shows Italian authorities surrounding the yacht. Mordashov, who was the CEO of steel company Severstal, has a net worth of nearly $30 billion, and was recently sanctioned by the European Union after Russia's invasion of Ukraine.

The yacht, according to SuperYachtFan, is worth over $50 million and is over 200 feet long. The vessel includes a helipad and can accommodate a dozen guests.

The move to target these assets comes as the U.S. Justice Department announced a new task force that will help enforce sweeping sanctions against Russian oligarchs. The task force will use various tools at its disposal, including cryptocurrency tracing, to track down assets to seize and prosecute those who violate the sanctions.

Meanwhile, the United States and its allies have placed what could be devastating sanctions on Putin and key Russian financial institutions, including the nation's central bank.

This story will be regularly updated if other yachts are seized. Please check back for updates.