The UK's Independent Commissioner's Office has declared its intention to fine Marriott International £99m (NZ$187m) for "infringements" of the General Data Protection Regulation.

In November 2018, a cyber incident was notified by Marriott to the ICO. A variety of personal data contained in approximately 339 million guest records globally were exposed, including 30 million residents of 31 countries in the European Economic Area.

After an investigation, the ICO said the issue appeared to arise in 2014 when the systems of the Starwood hotels group were compromised. Marriott subsequently acquired Starwood in 2016, but the theft of customer information was not discovered until 2018.

The ICO said Marriott had failed to undertake sufficient due diligence when it acquired Starwood and should have done more to ensure its IT systems were secure. The total fine to be issued is £99,200,396 (NZ$187,201,559).

“The GDPR makes it clear that organisations must be accountable for the personal data they hold,” said Elizabeth Denham, the information commissioner. “This can include carrying out proper due diligence when making a corporate acquisition, and putting in place proper accountability measures to assess not only what personal data has been acquired, but how it is protected.”

Marriott is contesting the fine. In a statement released on Tuesday, Marriott International's President and CEO, Arne Sorenson, said: "We are disappointed with this notice of intent from the ICO, which we will contest.  Marriott has been cooperating with the ICO throughout its investigation into the incident, which involved a criminal attack against the Starwood guest reservation database.

“We deeply regret this incident happened.  We take the privacy and security of guest information very seriously and continue to work hard to meet the standard of excellence that our guests expect from Marriott.”

The Starwood guest reservation database that was compromised is no longer used for business operations.

The ICO can fine a company up to 4 percent of its global annual revenue for a breach under the GDPR. This is a significant increase on the previous maximum fine of £500,000 (NZ$943,438).