The shuttle blasted off from Florida, US, at 1719 local time (2219 GMT) on Thursday without incident.

The launch, the first following 11 September, went ahead with unprecedented security in place.

"We're all aware that for over 200 years and certainly over the last two months, freedom rings loud and clear across this country," Endeavour's commander, Dominic Gorie, said just before the engines ignited. "But right here and right now, it's time to let freedom roar. Let's light them up."

The launch was scheduled for last Thursday but a jammed docking mechanism on the ISS and bad weather had forced a lengthy postponement.

Flag cargo

Unprecedented security surrounded the launch. A no-fly zone was established 35 miles (56 kilometres) around the launch pad and the six astronauts and one cosmonaut were escorted to the orbiter by guards with automatic rifles.

Endeavour will dock with the ISS on Friday. Its main task is to drop off Expedition Four - Ukrainian-born commander Yuri Onufrienko and US astronauts Carl Walz and Daniel Bursch - who will man the ISS until May of next year.

The shuttle will return the current platform crew - Expedition Three - who have been in orbit since August.

American Frank Culbertson and Russians Vladimir Dezhurov and Mikhail Turin were in space at the time of the 11 September attacks and photographed the smoke trail coming from the burning World Trade Center as they moved 200 miles (320 km) overhead.

The shuttle is carrying New York City police and fire department badges and patches, and flags from the World Trade Center, the Pentagon and Pennsylvania.

Thousands of small American flags are also on board. These will be given to the families of those killed on 11 September and to the survivors of the attacks.