UPDATE 1-Gazprom output may fall 18 pct in 09-report

* 2009 volume output seen between 450-510 bln cubic metres

* In 2008 Gazprom produced 550 bln cubic metres of gas

(Adds quote, details, background)

MOSCOW, May 22 (Reuters) - Russia's Gazprom (GAZP.MM) faces a drop in natural gas output of up to 18 percent this year the deputy head of the gas export monopoly, Alexander Ananenkov, said on Friday, Interfax reported.

"The volume of gas production, considering real consumption on the market, could be 450 to 510 billion cubic metres of gas," the news agency quoted him as saying.

In 2008 Gazprom produced 550 billion cubic metres of gas, so a decline to 450 bcm would mean a decline of 18.2 percent.

Gas production at the state-controlled firm fell 28 percent last month to the lowest level in a decade in response to plummeting demand in Europe. [ID:nL2356210]

Analysts expected a recovery only in the second half of 2009 when gas prices were expected to fall in line with the lower oil price, which they follow after a lag of six to nine months.

Cash-strapped consumers delayed purchases until gas was cheaper, and switched to alternative fuels.

Around 80 percent of Russian gas output comes from Gazprom, which supplies a quarter of Europe's gas and is the world's largest producer of the fuel. (Reporting by Simon Shuster)