UPDATE 1-Blackstone files Travelport IPO in London-sources

(Adds byline, details of listing in London, background)

By Michael Flaherty

NEW YORK Dec 3 (Reuters) - Blackstone Group LP (BX.N) has filed to publicly list Travelport, its travel services group, on the London Stock Exchange in an offering that could raise around $2 billion, sources said on Monday.

Blackstone bought Travelport from conglomerate Cendant Corp in August 2006 for $4.3 billion. Since the deal closed, Blackstone has cut costs and made the company profitable. UBS AG is the bank leading the London offering, sources said.

"We don't comment on rumor or speculation," Travelport spokesman Elliot Bloom said on Monday. UBS and Blackstone declined to comment.

Travelport, formerly Cendant Travel Distribution Services, operates one of the largest global distribution service (GDS) businesses in the world through its Worldspan and Galileo brands and provides travel content through its GTA brand.

A GDS provides computer hardware and software to travel agencies for plane, hotel and car reservations.

Travelport also owns a majority stake in online travel company Orbitz Worldwide Inc (OWW.N). The company has around 7,500 local employees, according to its Web site. The separation of Travelport and Orbitz were part of Cendant's break-up.

New York-based Travelport agreed to buy Atlanta-based rival Worldspan last December in a deal that valued Worldspan at around $1.4 billion. Travelport won European Commission approval in August to go ahead with the deal.

Including Worldspan, the company said it has around $3.4 billion in revenues.

Travelport has a significant portion of its business in the United Kingdom, which is partly why it's listing shares in London, according to people familiar with the offering.

Another reason is that London's public listing process allows the company to market the business to analysts prior to the pricing. That may help investors better understand the GDS business before the stock hits the market, according to the sources.

In addition, the U.S. market did not give a warm welcome to Orbitz. Since the company went public in July, its stock has lost nearly one-half of its value, closing at $8 per share on Monday. It hit a 52-week high of $14.95 last July.

Blackstone will keep a significant stake in Travelport after the IPO, sources said. (Reporting by Michael Flaherty; Editing by Jeffrey Benkoe)