Takeda Pharmaceutical Co <4502.T>, Japan's largest drugmaker, said on Thursday it would buy privately held Swiss rival Nycomed for 9.6 billion euros ($13.6 billion) as it seeks to expand in Europe and emerging markets.

The deal marks the biggest overseas purchase by a Japanese company since Japan Tobacco <2914.T> paid $19 billion for Britain's Gallaher and is Takeda's second major deal after purchasing U.S. cancer specialist Millennium Pharmaceuticals for $8.8 billion in 2008.

The purchase would offer Takeda access to lung-disease drug Daxas, just approved in the United States, and a portfolio of over-the-counter consumer products.

Takeda, known for its top-selling diabetes drug Actos, will finance part of the transaction with a 600-700 billion yen loan. The deal had been expected after being flagged by financial sources last week.

Nycomed is majority owned by four private equity firms, led by Nordic Capital with 41 percent. Credit Suisse's DLJ Merchant Banking has 25.6 percent, Coller International Partners 9.7 percent and Avista 8.9 percent.

Its lung drug roflumilast, known as Daxas in Europe and Daliresp in the United States, is the first in a new class of treatment for chronic obstructive pulmonary disease, a common breathing disorder often caused by smoking.

After some delays, it won U.S. approval in March where Forest Laboratories has the marketing rights. In Europe, Merck & Co has marketing rights.

Takeda has unsuccessfully explored takeovers of other European drugmakers previously, including Organon and Sweden's Meda AB , according to sources.

($1 = 0.707 Euros)

(Reporting by James Topham; Editing by Edwina Gibbs)