UPDATE 1-Emergent gets anthrax vaccine expiry date extension

* FDA approves BioThrax extended expiry date to 4 years

* Says entitled to $30 mln milestone

* Says milestone to be recognised in Q2

* Says approval triggers price rise for future deliveries

June 10 (Reuters) - Emergent Biosolutions Inc (EBS.N) said the U.S. health regulator approved an extension of expiry date for its anthrax vaccine to four years from three years, sending its shares up as much as 11 percent.

"We are pleased that the U.S. Food and Drug Administration has approved the 4-year expiry dating of BioThrax, as this extends the ability of the U.S. government to store our product in the nation's Strategic National Stockpile," Chief Executive Fuad El-Hibri said in a statement.

The company, which supplies the only approved anthrax vaccine to the United States Strategic National Stockpile (SNS), said the extension entitled the company to a $30 million contract milestone for doses previously delivered to the SNS.

The Strategic National Stockpile, or SNS, is a stockpile of medical supplies intended to protect Americans in case of public emergencies like a flu outbreak, terrorist attacks or earthquakes that are severe enough to cause local supplies to run out.

So far, the company has delivered 33 million doses to the SNS.

The company, which expects the milestone to be recognised as the second quarter revenue, said the approval also triggerred a price increase for future deliveries of the vaccine in the current contract.

Last year, the company inked a follow-on mutli-year contract with the HHS, worth $364 million to $404 million for the supply of 14.5 million additional doses. Emergent said the price rise was also applicable for the follow-on contract.

Shares of the Rockville, Maryland-based company rose touched a high of $15.31 and shed some of its gains to trade up 7 percent at $14.72 Wednesday on the New York Stock Exchange. (Reporting by Vidya L Nathan in Bangalore; Editing by Jarshad Kakkrakandy)