New Zealand's richest man, Graeme Hart, is exploring a sale of SIG Combibloc Group that could value the world's second largest maker of drink cartons at around $5 billion, according to people familiar with the matter.

Hart's packaging conglomerate, Reynolds Group Holdings, has hired Goldman Sachs Group  to explore alternatives for SIG, including a potential sale, the people said on Monday.

SIG, which Hart acquired for $2.3 billion in 2007, is in the early stages of preparing a sale process and is expected to attract interest mainly from private equity firms, the people added.

SIG has annual earnings before interest, tax, depreciation and amortization (EBITDA) of around $500 million and may fetch close to 10 times that amount in a potential deal, the people said, asking not to be identified because the deliberations are private.

Representatives for Reynolds and SIG did not immediately respond to requests for comment. Goldman Sachs declined to comment.

A sale of SIG, which is based in Neuhausen am Rheinfall, Switzerland, would underscore Hart's efforts to trim the $18 billion debt pile his packaging empire has accumulated through leveraged buyouts.

Those deals include the $6 billion acquisition of Pactiv Corp, the maker of Hefty trash bags, in 2010, and the $4.5 billion takeover of plastic container producer Graham Packaging Co in 2011.

SIG manufactures aseptic carton packaging that allows juices, milk, soups and sauces to be stored for a long period of time without refrigeration. The company has around 5,100 employees in 40 countries.

SIG ranks second in global food and drink carton packaging sales, behind Sweden's Tetra Laval international SA.

The company has been grappling with lower sales and higher manufacturing and raw material costs, particularly for resin, according to a presentation on the Reynolds Group website.

Hart, 59, has a net worth of $7 billion, according to Forbes.-Reuters