Washington  - The space shuttle Discovery blasted off for a construction mission to the International Space Station on Sunday after weeks of delays.

Discovery took off at 7:43 pm (2343 GMT) from the Kennedy Space Centre at Cape Canaveral, Florida.

The launch was to have gone off Wednesday but a fuel leak caused it to be scrapped at the last minute. Earlier concerns about valves that control the flow of gaseous hydrogen had already delayed the mission for weeks.

The Discovery is to deliver the fourth and final solar panel to the International Space Station on a construction mission that will enable it to double the size of its crew to six astronauts.

Discovery has seven astronauts on board, including Japanese crew member Koichi Wakata, who is slated to join the permanent crew on the orbiting space station. (dpa)