* Investigation related to $50 mln payment to little-known company
* Wynn says not notified by authorities (Includes comment from Macau corruption commission)
HONG KONG, July 11 (Reuters) - Macau's corruption agency said on Friday it is examining a land deal relating to Las Vegas mogul Steve Wynn's upcoming $4 billion casino in the world's biggest gambling hub.
The anti-graft body is investigating after the U.S.-based International Union of Operating Engineers asked the Macau government to provide more details on how a little-known company secured rights to land before it was granted to Wynn.
The land is now part of Macau's multi-billion-dollar gambling precinct known as the Cotai Strip, where Wynn's Wynn Macau Ltd is set to open its second casino resort in 2016.
"The case is now under investigation," the anti-graft agency said in an email to Reuters, adding it was not able to comment further on the issue.
Wynn, one of six licensed casino operators in the southern Chinese territory, is on track to open its opulent Wynn Palace project in the first half of 2016, featuring facilities such as a massive lake and air-conditioned gondolas.
Wynn Resorts said it had not been contacted by any government agencies on the issue. "If we were we would fully cooperate," the company wrote in an email to Reuters.
The union, which counts hundreds of Las Vegas-based engineers among its members, has been pushing for greater transparency around Wynn's land purchases in Macau. In particular, it has expressed concern about a $50 million payment Wynn was asked to make to an entity with possible links to politically connected officials in order to establish itself on the Cotai Strip.
Macau's Land, Public Works and Transport Bureau said on Wednesday the land grant followed legal procedures, according to Macau media.
Wynn has said in company filings it agreed in 2008 to pay $50 million to Macau-registered Tien Chiao Entertainment and Investment Co Ltd in exchange for the company relinquishing its rights to what is now Wynn's Cotai site.
Tien Chiao's identity is not clear to multiple Macau lawyers and analysts who Reuters has interviewed on the matter. The company was incorporated in October 2005, according to registry filings.
The two registered company representatives are Ho Hoi, a Chinese national with a Hong Kong ID number, and Chinese national Zhang Luchuan who lives in Beijing. It has not been possible to locate either of them.
(Reporting by Farah Master; Editing by Stephen Coates)