A cyberattack that broke into a police account and accessed work-related contact details of all Dutch police officers was almost certainly carried out by hackers working for a foreign government, the justice minister told lawmakers.

Dutch intelligence agencies “consider it highly likely that a state actor is responsible,” Justice and Security Minister David van Weel wrote in a letter to lawmakers on Wednesday night about the breach, which was first revealed last Friday.

He added that “police, together with national security partners, are doing everything they can to protect police employees and prevent further damage.”

Van Weel did not give further details, citing an ongoing investigation into the data breach. The Dutch police force is the country’s biggest employer with nearly 63,000 staff.

Nine Kooiman, chair of the Netherlands Police Union, called the hack “a nightmare. It is now important to protect data, protect colleagues” and track down the perpetrators.

The government said last week that the hack did not reveal personal details of police officers beyond their names or details about ongoing investigations.

Dutch police chief Janny Knol said she had spoken to staff about their concerns following news of the data breach, noting they were “concerns that I share, because in order to ensure safety outside, you have to feel safe inside.”

The Dutch General Intelligence and Security Service warned last year in its annual report that countries including China and Russia were actively engaged in cyberattacks and espionage targeting national interests in the Netherlands.

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