The sixth launch this year of an Ariane 5 rocket had been initially planned for December 11 between 12:35 and 1:45 a.m. Moscow time (21:35-22:45 GMT December 10), but was later rescheduled for December 21 at 0:51 Moscow time (21:51 GMT December 20).
The rocket is due to put into orbit two satellites, HOT BIRD TM-9 and W2M, for the European communications and satellite television operator Eutelsat.
French media earlier cited Arianspace SA as saying that the initially scheduled launch on December 11 had been delayed due to mass protests in French Guiana against high gasoline prices.
Kourou is located 50 km (31 miles) from the town of Cayenne on the Atlantic coast of South America.
The European Space Agency launch facility is mainly used to launch geostationary satellites into orbit. The first launch of a Russian Soyuz-ST rocket from Kourou is due in late 2009.
The center's proximity to the equator will allow the modernized Russian rocket to orbit heavier satellites than from the Baikonur space center in Kazakhstan and Plesetsk in northern Russia.
