Starwood Hotels, which operates the Sheraton and Westin chains, said Friday that hackers had infected payment systems in some of its establishments, potentially leaking customer credit card data.

The hack occurred at "a limited number" of its hotels in North America, according to Starwood, whose other well-known chains include St Regis and W Hotels.

Starwood said that an investigation by forensic experts concluded that malware was detected in some restaurants, gift shops and other points of sale systems at hotels.

"The malware was designed to collect certain payment card information, including cardholder name, payment card number, security code and expiration date," the group said in a statement.

"The affected hotels have taken steps to secure customer payment card information and the malware no longer presents a threat to customers using payment cards at Starwood Hotels."

Sergio Rivera, Starwood's president for the Americas, said the company has been working with law enforcement and payment card organizations.

"We want to assure our customers that we have implemented additional security measures to help prevent this type of crime from reoccurring," he said.