If the deal goes through it would be the latest reshuffling of the mix in the packaging industry, which has experienced a wave of consolidations over the past year.
Canada-based Alcan will sell its packaging arm following its agreed-upon $38.1-bn takeover by mining group Rio Tinto, Reuters stated, quoting an unnamed source.
The source said the deal, which is not yet final, could be announced some time in the next few weeks.
Packaging company Bemis Co. was also interested in the unit, Reuters stated.
Sealed Air, which had sales of $4.3bn last year, would double in size if the purchase goes through.
Alcan and Bemis have not responded to the reports.
Alcan manufactures packaging for the food, pharmaceuticals, cosmetics and tobacco industries.
The packaging unit had sales of $3.2bn last year.
Earlier this year Rexam completed its divestment of its European glass packaging business and is now preparing for its takeover of Owens-Illinois' plastics division.
Ardagh Glass bought Rexam's glass container business for €660m earlier this year.
The purchase allows Ardagh to double in size to become Europe's third largest glass container supplier.
The deal will reduce competition in the glass container market, giving Ardagh 18 per cent of the European market and more power over pricing.
The move by both packaging giants marks part of an ongoing reorganisation in the market.
Companies are either moving to focus on profitable areas of the market, or, as in the case of Rexam, try to offer a range of packaging formats and materials to their customers.
O-I Plastics, the division being purchased by Rexam, specialises in healthcare packaging and plastic tops.
O-I Plastics is a US manufacturer of rigid plastic healthcare packaging and plastic closure systems.
The unit had sales of US$760m in 2006 and an underlying profit of US$114m. Rexam's clients include Anheuser-Busch, Cadbury-Schweppes, Carlsberg, Coca-Cola, Heineken, InBev, Pepsi, Proctor & Gamble, Red Bull and SABMiller.