* Q1 sales $12.5 bln vs $12.6 bln in Reuters poll
* Q1 sales from continuing operations $11.9 bln, down 7 pct
* Q1 core operating income down 4 pct yoy
* Maintains 2015 guidance (Recasts, adds detail)
ZURICH, April 23 (Reuters) - Swiss drugmaker Novartis on Thursday posted declining sales in the firstquarter and cautioned that dollar strength may be abigger-than-expected drag on full-year figures.
The Basel-based firm said the strong dollar -- its reportingcurrency -- would shave 10 percent off 2015 sales and 13 percentfrom core operating income if April exchange rates continue forthe rest of the year.
In January the company forecast the 2015 currency hit wouldbe 7 percentage points on net sales and 12 percentage points oncore operating income from continuing operations.
Novartis maintained its 2015 guidance of mid-single-digitsales growth in 2015 and high-single-digit growth in coreoperating income after stripping out the impact of currencyfluctuations.
The group reported a 7 percent year-on-year fall infirst-quarter net sales in continuing operations to $11.9billion, while sales rose 3 percent at constant currencies.Total group net sales were $12.5 billion.
Novartis generated net income from continuing operations of$3.2 billion, down 4 percent in dollar terms on the same periodlast year but up 8 percent at constant currencies. Total groupnet income was $3.1 billion.
Analysts in a Reuters poll had forecast total group netsales of $12.6 billion and group core net income of $2.9billion.
Cross-town rival Roche on Wednesday beatexpectations for the first quarter with a 3 percent rise insales on a strong showing from its cancer drugs and a recentlylaunched treatment for a deadly lung disorder. (Reporting by Joshua Franklin; Editing by Michael Shields)