Some 200,000 people in the Netherlands have been affected by a hack at the fitness chain Basic-Fit, the organisation said on Monday.

In total, details about one million of the chain’s 4.8 million members in six European countries have been stolen, the company said. The information includes bank details, names, addresses, email addresses and dates of birth.

The company does not store copies of its members’ IDs, and no passwords, medical details or health complaints were hijacked.

The hack does not involve branches of Clever Fit, which was taken over by Basic-Fit last October, or the franchise network, which uses a separate system, news agency Reuters reported.

The company says it ended the hack shortly after noting that the computer security system had discovered it. “We saw the system had been approached by an outside source and details were being downloaded,” the company said. “We are now trying to establish who was behind it and how they managed to break in.”

Members whose details were stolen have been notified about the hack by email, which also warns people to beware of suspicious emails.

Earlier on Monday, it emerged that online travel agency Booking had been hit by a hack. Two months ago telecoms firm Odido confirmed that hackers had accessed personal data belonging to 6.2 million current and former customers, in one of the largest breaches ever reported in the country.