Ransomware gang Nova is threatening to leak more of the medical data it hacked at test processing lab Clinical Diagnostics unless the clinic pays “a large amount of money” within 11 days, the NRC reported on Sunday.

According to a message on the gang’s darknet page, the clinic in Rijswijk broke a supposed agreement not to involve the police. A police spokesman told the paper on Sunday they were “active in the background” after the clinic reported the matter last week.

The personal information of almost half a million people was accessed, most of them women who had participated in a screening for cervical cancer.

The gang removed the data of over 50,000 women from the dark web after Clinical Diagnostics paid an undisclosed sum, RTL Nieuws found, based on anonymous sources at Nova and the clinic.

According to the NRC, Nova is a relatively new ransom gang that has successfully hacked a large number of victims in a relatively short period, including the local authorities in Pisa in Italy.