The final scheduled launch of space shuttle Discovery was delayed another 24 hours to next Wednesday so repairs can be made to a pressurization system, NASA said.

The US space agency had already pushed back the launch by a day to Tuesday.

If technicians are able to finish their repairs as planned, Discovery and its six American astronauts will now launch from Florida's Kennedy Space Center at 3:52 pm (1952 GMT) Wednesday, NASA test director Jeff Spaulding said.

The flight to the orbiting International Space Station is the fourth and final shuttle flight of the year, and the last scheduled for Discovery, the oldest in the three-shuttle fleet that is being retired in 2011.