German authorities have reportedly seized a $600m (£448m) yacht belonging to Russian billionaire Alisher Usmanov, while France has impounded a yacht belonging to Igor Sechin, the Rosneft chief, amid an escalating crackdown on oligarchs.

The 156-metre yacht Dilbar, the world’s largest by gross tonnage, was seized by authorities in a Hamburg shipyard.

The boat had been in the shipyard of engineering firm Blohm + Voss undergoing renovation since late October, Forbes reported, adding that the German government had frozen the asset and employees did not turn up for work on Wednesday.

Mr Usmanov was included on a list of ultra-wealthy Russians targeted for sanctions by the EU following the country’s invasion of Ukraine last week.

The metals tycoon and former Arsenal co-owner is also reported to be targeted in a package of sanctions being prepared by the US Treasury Department.

It comes a day after Everton Football Club cut commercial ties with Mr Usmanov, who had close links with its majority shareholder Farhad Moshiri.

The club said it was ending all commercial agreements with the tycoon’s USM Holdings, as well as telecoms firm Megafon and smartphone maker Yota.

Mr Usmanov bought Dilbar in 2016 for a reported $600m from German shipbuilder Luerssen, which custom-built it for him over a year.

The luxurious vessel, which weighs 15,917 tonnes, is usually manned by a crew of 96 people and boasts the largest swimming pool ever installed on a yacht.

It also has two helicopter pads, a sauna, a beauty salon and a gym and can host up to 24 people in 12 suites.

The yacht is part of Mr Usmanov’s vast fortune, which is estimated at $19.7bn by Bloomberg. 

It spans stakes in steel giant Metalloinvest and Chinese electronics giant Xiaomi, as well as holdings in a range of smaller telecoms and media firms. He also owns Russian newspaper Kommersant and was an early investor in Facebook.