ST. PETERSBURG, November 7 (RIA Novosti) -- A special cargo ship carrying parts of two Russian Soyuz-ST rockets on Saturday left the port of St. Petersburg, heading to the Kourou space site, the Russian space agency said.

Soyuz-ST is a modernized version of the Soyuz-2 rocket developed by the Samara-based Progress design bureau specifically for launches from the Kourou space center in French Guiana.

The Kourou launch site is intended mainly for the launch of geostationary satellites. Its proximity to the equator will enable the Soyuz-ST to put into orbit heavier satellites than those launched from Baikonur in Kazakhstan and Plesetsk in northern Russia.

Russia's Federal Space Agency Roscosmos and French satellite launch firm Arianespace signed a contract last year to launch 10 Russian Soyuz-ST carrier rockets from a separate launch pad in French Guiana near Sinnamari, a village 10 kilometers (6 miles) north of the site used for the Ariane-5, the main European-made booster.

The contract is estimated at $300-$400 million and stipulates at least three launches per year.

Rene Pischel, head of the European Space Agency's (ESA) office in Russia said in August that the construction of the spaceport for Soyuz launches at Kourou is in its final stages and a supply tower is currently being assembled.

The first launch of the Soyuz-ST rocket from Kourou is scheduled for April 2010.