Belgium's Solvay SA (SOLB.BT) confirmed Monday it is selling its pharmaceutical activities to U.S. rival Abbott Laboratories (ABT) for about EUR5.2 billion and will reinvesting the proceeds to expand in its plastics and chemicals businesses.

Abbott will pay about EUR4.5 billion in cash, with up to another EUR300 million if certain milestones are met between 2011 and 2013. The U.S. pharma company is also assuming EUR400 in liabilities from Solvay, the Brussels-based company said in a statement.

"Solvay will reinvest the proceeds in organic and sizable external growth, focused on long term value creation," the company said. This will be done in focusing on its other two core businesses, plastics and chemicals, and in geographical regions that offer strong growth potential, it added.

Solvay shares closed at EUR74.73 on Friday. They have gained 41% since the beginning of the year.

-By Alessandro Torello, Dow Jones Newswires; +32 2 741 14 88; alessandro.torello@dowjones.com