Google has confirmed it is working to fix an attack on big brand hotels including Marriott and Hilton, which sees links to their websites redirected to a third party.
The search giant declined to make an official comment except to say it was aware of the issue.
Tnooz was contacted anonymously late-last week with information showing some hotel URLs had been compromised.
Google would not comment on how long it had known about the issue or how it had happened.
The apparently hijacked links, which list "roomstobook" as the website address under the property details, appear in Google+ Local which also serves results to Google Maps and in search.
The "roomstobook" link in turn directs users to hotel reservation site, Hotelswhiz.
A search for Roomstobook.net (one of the URLs used) redirects to the Hotelswhiz site, although it is not known if the apparent spam attack has anything to do with the hotel booking site.
Screenshots forwarded to Tnooz, show listings for big brands such as Hilton and Holiday Inn with the roomstobook (.net or .info) URL next to them.
The following screenshot, showing the roomstobook.info URL against Holiday Inn properties, was taken a few days ago:
A second screenshot taken today (15 January) shows that although the "roomstobook" address is still visible, there is also a "book at HolidayInn.com message".
NB: See this report from Search Engine Land for more detailed analysis.
NB2: Tnooz has attempted to contact Hotelswhiz for comment on the story.
NB3: Anti-hijack image via Shutterstock.