AMSTERDAM, Feb 12 (Reuters) - Odido, the former business of T-Mobile in the Netherlands, said on Thursday that personal information from more than six million accounts had been exposed in a hack, one of the largest such incidents in the country.

"Odido was recently hit by a cyberattack carried out by cybercriminals," the company said in an email sent to affected customers. "Based on the investigation, we believe that your data may have been affected."

The company said stolen information included customer names, telephone numbers, e-mail addresses, bank account numbers, birth dates and passport numbers.

The company said it first began investigating a possible hack on February 7 with internal and external experts, finding that it was affecting the system it uses to contact its customers.

"Unauthorized access to the system was terminated," the company said, adding that it is safe for customers to use their phones. The incident has been reported to the Dutch privacy and data protection watchdog AP.

Odido, which was purchased by private equity firms Apax and Warburg Pincus in 2021, has around 8 million customers and competes with KPN KPN.AS and VodafoneZiggo on the Dutch market.

(Reporting by Toby Sterling; Editing by Kirsten Donovan )

((amsterdam.newsroom@thomsonreuters.com))