The talks are over the majority of Linde's gases business in North America and certain Linde and Praxair assets in South America, Linde said on Thursday.

The assets have an enterprise value (equity plus debt) of more than $3 billion, a source familiar with the matter told Reuters.

Linde and Praxair, which supply a wide range of gases from oxygen to helium, need to sell assets to gain regulatory approval for their all-share merger which will create a global leader in the sector.

Praxair this month agreed to sell its European gases business to Japanese rival Taiyo Nippon Sanso Corp <4091.t> for 5 billion euros ($5.8 billion).

Sources had told Reuters last month that private equity firm Carlyle Group LP was the front-runner for Linde's U.S. assets, which are seen as worth about $3.3 billion.

But they also said other bidders, such as Messer, had been given the opportunity to improve their offers.

Two people familiar with the matter told Reuters that an announcement could be made this week.

Linde said any deal would still need the approval of the relevant boards of the parties involved.

Linde and Praxair are hoping to complete their merger this year. The transaction still requires regulatory approval in the European Union and the United States.

German magazine WirtschaftsWoche earlier reported that Messer was the preferred bidder for the assets.

($1 = 0.8565 euros)

(Reporting by Maria Sheahan; Additional reporting by Alexander Huebner and Arno Schuetze; Writing by Caroline Copley and Maria Sheahan; Editing by David Goodman and Mark Potter)

By Maria Sheahan