An unmanned Ariane rocket has successfully blasted off from French Guiana and is now on its way to the International Space Station (ISS).

The modified launcher took off at 9.51pm on Wednesday night from Europe's spaceport in Kourou.

Over an hour after launch a 20 tonne cargo vessel separated from the rocket and is due to dock at the ISS on Feb 24.

It is the heaviest payload ever launched aboard an Ariane. A first attempt to launch the rocket was scrubbed on Tuesday because of a technical problem

The vessel, dubbed "Johannes Kepler" in honour of the visionary 17th century German astronomer and mathematician, is the second Automatic Transfer Vehicle (ATV) that Europe has committed to its participation in the ISS programme.

The ATV was designed to deliver fuel, food, clothing and oxygen to the ISS crew as well as spare parts.

The ATV will remain attached to the space station for more than three months as astronauts remove its cargo and fill it with rubbish from the station.

It will then be thrust back toward earth, burning up on re-entry. Any remaining debris will be targeted to a remote area of the Pacific Ocean.

The ATV has three times the cargo capacity of Russia's Progress vehicle and was developed by the ESA as part of a barter arrangement with Nasa.

Instead of paying cash for its share of the station's common operating costs and also to secure additional astronaut access, ESA is providing the ATV and other components.

Its role will be of increasing importance as American space shuttles are scheduled to be taken out of service after three more missions.