(Reuters) - Humira, the best-selling arthritis drug that forms the cornerstone of Abbott Laboratories' pharmaceutical business, has been approved in Europe for ulcerative colitis, the U.S. drugmaker said on Wednesday.

The green light from the European Commission follows a positive opinion from the European Medicines Agency in February and marks the seventh indication for Humira in the European Union since its first approval in 2003.

Humira, one of the world's biggest-selling drugs with sales forecast by analysts to be around $9 billion this year, is the first self-injectable biologic therapy for ulcerative colitis, a chronic disease that causes ulcers in the colon.

(Reporting by Ben Hirschler; Editing by David Holmes)