Takeda Pharmaceutical, Japan's largest drugmaker, will announce the 1 trillion yen ($12 billion) purchase of closely held Swiss rival Nycomed on Wednesday as it seeks to expand in Europe and emerging markets, Japanese business daily Nikkei reported.

The purchase would also give Takeda, known for its top-selling diabetes drug Actos, access to lung-disease drug Daxas, just approved in the United States, and a portfolio of over-the-counter consumer products.

A Takeda spokesman declined to confirm or deny the report. Sources with direct knowledge of the matter told Reuters Takeda was in talks to buy the Swiss firm and that the Japanese drug maker had approached a number of Japanese lenders, who were prepared to help finance the deal.

If agreed it would be the biggest overseas purchase by a Japanese company since Japan Tobacco paid $19 billion for Britain's Gallagher.

Takeda, which has around 874 billion yen in cash and marketable securities at hand, has previously said it would be willing to take on debt for future deals.

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

In emerging markets, Takeda initially plans to sell respiratory as well as other prescription and generic drugs developed by Nycomed, the Nikkei reported.

The Swiss drugmaker is well-placed to tap emerging markets, which made up nearly two-fifths of its revenue in 2010 and should make up 60% of sales by 2015. Emerging markets sales leapt 30% last year.

Nycomed chief Hakan Bjorklund has since 2008 talked of a possible IPO and in 2009 the Wall Street Journal reported that Goldman Sachs was hired to explore a sale of the company.

The group, which is now being advised by Goldman and Credit Suisse, also fielded approaches from several other suitors, one person familiar with the matter said.

Takeda, which sources said Thursday had hired Deutsche Securities as an adviser, may be able to reap synergies which could run to hundreds of millions of euros a year.

Takeda said on May 11 it expects operating profit to increase .2% to 390 billion yen in the year to March 2012. It sees operating profit falling to 240 billion yen two years later, hurt by patent expiry on Actos.($181.425 Japanese Yen)