Holiday Inn hotels hit by cyber-attack
IHG, which has some of the world's largest hotel chains, issued a statement saying it was investigating "unauthorised access" to a number of its technology systems.
The UK-based company said its "booking channels and other applications" had been disrupted since Monday.
It manages the Holiday Inn, Crowne Plaza and Regent hotels.
"IHG is working to fully restore all systems as soon as possible," the company said.