(Reuters) - Private equity firm Onex Corp (>> ONEX Corporation) is looking to sell Sitel Worldwide Corp in a deal that could value one of the world's largest call center operators at close to $1 billion, including debt, according to people familiar with the matter.

Onex is working with investment bank Goldman Sachs Group Inc (>> Goldman Sachs Group Inc) on an auction for Sitel, two of the people said, asking not to be identified because the deliberations are private.

Onex and Sitel did not respond to requests for comment while Goldman Sachs declined to comment.

Market intelligence firm International Data Corporation estimates that the global customer care services market, in which Sitel competes, will grow from $64 billion in 2014 to $81 billion in 2018, as companies seek to cut more costs.

Nashville, Tennessee-based Sitel outsources customer service, technical support, back office support and other services for 225 corporate clients. It operates 108 facilities in 21 countries, supporting customers in 40 languages.

The company reported $1.4 billion in revenue and $117.7 million in adjusted earnings before interest, tax, depreciation and amortization in 2014.

Onex took Sitel private in 2007 for $450 million, including debt. Onex invested a further $51 million to buy preferred shares of Sitel in 2008, and an additional $69 million shares in 2014. It had an 86 percent stake in Sitel as of the end of December.

(Reporting by Greg Roumeliotis in New York; Editing by Lisa Shumaker)

By Greg Roumeliotis

Stocks treated in this article : Goldman Sachs Group Inc, ONEX Corporation