By Carl O'Donnell

April 8 (Reuters) - Biogen Inc, one of the world's largest biotechnology companies, is exploring a sale of its hemophilia treatments, as it increases its focus on core therapeutic areas, according to people familiar with the matter.

The potential sale of the assets, long seen as unusual fits relative to the company's broader portfolio, come as Biogen implements a sweeping restructuring program announced in October to cut costs and focus on core areas such as neurology and autoimmune diseases.

Biogen is working with an investment bank on the sale of the hemophilia assets, the people said this week. There is no guarantee that the discussions will lead to a sale, the people added.

These drugs collectively produced sales of about $500 million in 2015, the first full year in which they have been for sale.

The sources asked not to be identified because the sale process is confidential. Biogen declined to comment.

"With the majority of the restructuring now completed, there's a palpable reinvigorated focus on our key commercial initiatives and high-potential pipeline candidate," Biogen Chief Executive Officer George Scangos told analysts on the company's latest earnings call in January.

The potential divestment marks somewhat of an about-face for Biogen. In a February interview with trade publication Xconomy, Scangos said that he had decided to hold on to the products and try to build a platform around them.

Biogen now has two hemophilia products that have already obtained approval from the U.S. Food and Drug Administration, Alprolix and Eloctate.

"If all we were going to do was market those two compounds and let them run their life cycle then we should probably just sell them," Scangos said. "If we are gonna be in it we need to be making investments for the future and the next generation of products, and care about this."

Last year, Biogen made a small investment in its hemophilia platform, partnering with two Italian research institutions to develop gene therapies that treat the root causes of some types of hemophilia.

The hemophilia drugs' revenues could continue to grow significantly in coming years due to their potential for international expansion. In November, Eloctate was launched in Europe for the treatment of one type of hemophilia.

(Reporting by Carl O'Donnell; Editing by Bernard Orr)