(Bloomberg) -- German shipbuilder Lürssen, which makes military vessels as well as luxury yachts, has become the target of a ransomware cyberattack.

The Bremen-based company was attacked over the Easter holiday period, company spokesman Oliver Grün said Tuesday. “In coordination with internal and external experts, we immediately initiated all necessary protective measures and informed the responsible authorities,” he said by text message. 

The attack has brought large parts of Luerssen’s shipyard operations to a standstill, according to local news outlet Buten un Binnen which reported the incident earlier.

Lürssen has built several superyachts, including the world’s largest by volume, the 156-meter (512-foot) Dilbar, owned by a trust linked to Russian billionaire Alisher Usmanov. The company traces its origins back almost 150 years.

In a ransomware attack, a victim’s computer files are usually encrypted by parties who demand payment to unlock them. Ransomware perpetrators can also steal files and threaten to release them unless they receive payment.

Read more: ‘We Hacked the Hackers’: Hive Ransomware Seized in Global Sting

©2023 Bloomberg L.P.