The U.K. government Thursday ordered millions of doses of influenza treatments Relenza and Tamiflu from makers GlaxoSmithKline PLC (GSK.LN) and Roche Holding AG (ROG.VX) to provide treatment for up to half its population if a flu pandemic strikes.

The U.K. Department of Health said the deal will double the U.K.'s stockpile of antiviral flu drugs and make it the second European nation, after France, to have enough medicine to treat 50% of its citizens.

It ordered 10.6 million courses of treatment of Relenza from GlaxoSmithKline of the U.K. and 7.6 million of Tamiflu from Switzerland's Roche. The U.K.'s total stockpile now stands at 33.5 million doses of antivirals.

"The increased flu-drug stockpile means that we should be able to treat everyone who falls ill in a pandemic," said U.K. Public Health Minister Dawn Primarolo.

Precise financial terms are confidential, although a spokesman for GlaxoSmithKline said it is worth in excess of GBP100 million to the Brentford, England-based drug maker. He added the company is providing the doses at a discount to its normal price.

Roche said it will have the order delivered by March, but said it couldn't discuss financial terms.

The U.K. government previously had only Roche's Tamiflu in its stockpile, but the European Medicines Agency recommended governments don't rely on just one treatment because of emerging evidence of the bug's resistance.

At 1442 GMT, shares in GlaxoSmithKline were down 32 pence, or 2.6%, at 1,223 pence, slightly outperforming a lower FTSE-100 index, down 3.1%. Roche shares were down CHF3.70, or 2.2%, at CHF161.90.

Company Web site: www.gsk.com

-By Jason Douglas, Dow Jones Newswires; 44-20-7842-9272; jason.douglas@dowjones.com

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