NASA successfully deploys space station's inflatable room.

US space agency NASA successfully deployed the first experimental inflatable room attached to the International Space Station.

NASA Astronaut Jeff Williams began introducing air into the Bigelow Expandable Activity Module on Saturday afternoon, but he only filled air into the spacecraft for a very short time, ranging from one to 30 seconds, each time, Xinhua news agency reported.

In total, Williams opened the air valve 25 times for a total time of 2 minutes and 27 seconds to add air to the module in short bursts as flight controllers carefully monitored the its internal pressure.

"For safety, we re going slowly," the US space agency said on Twitter.

"Want to ensure expansion doesn't impart any force onto the Station structure itself."

The 1,400 kg Bigelow Expandable Activity Module (BEAM) was built by Las Vegas-based Bigelow Aerospace under a $17 million NASA contract.

When manual operations ended late Saturday night, the module added 1.5 metres in length to reach 1.7 metres beyond its packed configuration and an internal diameter of 3.2 metres, NASA said.

Then, Williams opened eight tanks of air stored within the BEAM, pressurising the module into full size -- more than 4 metres long and about 3.2 metres in diameter with 16 cubic metres of interior volume, NASA said.

Next week, leak checks will be performed on the BEAM to ensure its structural integrity, NASA said, adding that hatch opening and Williams' first entrance will take place about a week after leak checks are complete.

BEAM was launched to the orbiting lab last month in an effort to test and validate expandable habitat technology.

Inflatable habitats are designed to take up less room on a spacecraft, but provide greater volume for living and working in space once expanded, according to NASA.