* Slump eased slightly in March
* Output takes hit from dwindling euro zone demand
WARSAW, April 9 (Reuters) - Polish car production slumped an annual 24 percent in the first quarter following top manufacturer Fiat's announced layoffs at its Polish factory, industry monitor Samar said on Tuesday.
On a monthly basis, March saw the number of passenger cars and trucks produced in Poland fall 20 percent year-on-year, a slight improvement from February's 29 percent drop. Last year production fell 23 percent .
Nearly 99 percent of the cars assembled in Poland by producers, which also include General Motor's and Volkswagen, are sold abroad.
Production has taken a hit from dwindling demand in the euro zone, the country's main trade partner.
Car sales across Europe fell in the second month of the year to their lowest February level in at least 23 years, the Association of European Car Manufacturers (ACEA) said.
The drop in Polish car manufacturing adds a general economic slowdown.
Economic growth in Poland, the only European Union member to avoid a contraction in its economy since 2008, is seen by the central bank slowing to its lowest pace in 12 years in 2013.
Manufacturing output is expected to drop 2.1 percent in annual terms in March, a Reuters poll shows.
According to economists' estimates, car production accounts for around 7 percent of Poland's industrial production.