Private US firm SpaceX launched its unmanned Dragon capsule to the International Space Station on Friday, its third trip carrying supplies and equipment to the orbiting lab.

After three earlier delays, the Falcon 9 rocket and its Dragon capsule finally blasted off as planned at 3:25 pm (1925 GMT) from Cape Canaveral in Florida.

About 10 minutes after liftoff, the capsule separated from the second stage of the rocket before going into orbit.

"THAT. WAS. AWESOOMEEE," one person with the handle Petar Le Grand wrote after watching the launch live on SpaceX's website.

It marks the California-based company's third commercial resupply mission and fourth visit to the ISS, where it is due to deliver 2.2 tonnes of cargo.

Dragon is due to meet up with the space station on Sunday at 2314 GMT.

The mission had originally been scheduled for mid-March and was delayed due to a helium leak.

In all, SpaceX is due to complete 12 missions for the US space agency NASA.

Its first successful pilot launch, completed in May 2012, marked the first time a private vessel had docked at the ISS. It was followed by the company's first cargo mission in October 2012.