<p>Hyatt Hotels Corp said on Wednesday that its payment processing system was infected with credit-card-stealing malware in an attack discovered three weeks ago, the latest in a series of breaches at hospitality firms. Company spokeswoman Stephanie Sheppard said in an email late on Wednesday that the attack was discovered on Nov. 30. She did not say if the attackers succeeded in stealing payment card numbers, how long its network was infected or how many of the chain's 627 hotels were affected. "Customers should review their payment-card account statements closely and report any unauthorized charges to their card issuer immediately," she said. Hyatt, controlled by the billionaire Pritzker family, is the fourth major hotel operator to warn of a breach since October.</p>