German authorities said they have seized a massive superyacht in Hamburg after determining that it belongs to the sister of Russian oligarch Alisher Usmanov.

The Federal Criminal Police Office said that, after “extensive investigations” and despite “offshore concealment”, it had been able to determine that the owner is Gulbakhor Ismailova, Mr Usmanov’s sister.

Superyacht Dilbar was launched in 2016 at a reported cost of more than 648 million dollars (£493 million).

German police office said German authorities worked in Brussels to ensure that European Union sanctions applied to the owner.

It says the yacht can no longer be sold, rented or loaded.

The United States and the EU last month announced economic sanctions against Mr Usmanov, a metals magnate, over his ties to Russian President Vladimir Putin and in retaliation for the invasion of Ukraine.