The owners of Danish cleaning firm ISS have revived plans for a multi-billion euro flotation, asking banks to pitch for roles helping to list or sell the company, three people familiar with the matter said.

The owners -- Goldman Sachs Capital Partners and Swedish private equity fund EQT Partners -- are seeking to start a dual-track process toward an initial public offering (IPO) or sale later this year, the sources said.

ISS's size may limit the number of potential buyers and make a listing the most likely option.

ISS says it is one of the world's largest providers of facility services. It employs nearly half a million people in about 50 countries, who clean offices, cook school meals, guard buildings and operate call centres.

Goldman Sachs's private-equity arm and EQT bought ISS in a leveraged buyout in 2005 that valued it at $5.34 billion including debt, according to Thomson Reuters data.

Goldman Sachs and ISS declined to comment. An EQT spokesman did not return a request for comment.

ISS had adjusted earnings before interest, tax, depreciation and amortization (EBITDA) of 4.74 billion Danish crowns ($812 million) in 2009 on revenue of 69 billion.

While big differences in areas such as accounting standards or the spread of businesses covered make direct comparisons difficult, listed British companies Rentokil Initial Plc and Mitie Group offer some of the same services. They trade at enterprise values of about 6.8 and 7 times trailing EBITDA respectively, according to Starmine data.

This is not the first time the private equity duo have sought to cash in on their investment, and ISS is familiar to many investment banks. In June 2007, Merrill Lynch and Goldman bankers were hired to study the feasibility of an IPO.

Nordea advised ISS on its buyout in 2005, while Goldman, Citigroup and SEB Enskilda advised the acquirers. Deutsche Bank last year worked with Goldman to sell high-yield bonds for ISS.

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(Editing by Elaine Hardcastle and Dan Lalor)

($1 = 5.840 Danish crowns)