By Greg Roumeliotis

May 17 (Reuters) - Investment firm Investcorp Bank is exploring a sale of Polyconcept, hoping a deal will value the world's largest supplier of promotional products at more than $1.3 billion, including debt, according to people familiar with the matter.

Bahrain-based Investcorp is working with investment banks William Blair & Company LLC and Barclays Plc in the auction for Polyconcept, which is currently in its second round of bidding and has attracted interest from private equity firms, the people said this week.

Polyconcept has 12-month earnings before interest, tax, depreciation and amortization of close to $130 million, the people added.

The sources asked not to be identified because the sale process is confidential. Investcorp and Barclays declined to comment, while Polyconcept and William Blair did not respond to requests for comment.

Based in Roelofarendsveen, Holland, Polyconcept makes and distributes promotional items such as pens, watches and mugs, as well as decoration. Most of its products are manufactured in Asia, according to credit ratings agency Moody's Investors Service Inc.

Polyconcept is a supplier of promotional products to several hundred thousand companies, ranging from small businesses to global corporations, through a network of advertising specialty distributors, according to its web site.

Investcorp acquired control of the company from buyout firm BC Partners Ltd in 2005.

(Reporting by Greg Roumeliotis in New York; Editing by Bernard Orr) ((Greg.Roumeliotis@thomsonreuters.com; +1 646 223 6022; Reuters Messaging: greg.roumeliotis.thomsonreuters.com@reuters.net))