WASHINGTON, March 27 (Xinhua) -- U.S. space agency NASA said Monday that it has canceled the first all-female spacewalk, citing the size of spacesuits as a reason.

Two female NASA astronauts, Christina Koch and Anne McClain, had been scheduled to perform the historic mission on Friday.

However, after consulting with McClain, who conducted a spacewalk with her male crewmate Nick Hague on March 22, mission managers decided to adjust the assignments, "due in part to spacesuit availability" on the International Space Stations, said NASA in a statement.

"McClain learned during her first spacewalk that a medium-size hard upper torso - essentially the shirt of the spacesuit - fits her best. Because only one medium-size torso can be made ready by Friday, March 29, Koch will wear it," the statement said.

However, NASA clarified Tuesday in a tweet that it has more than one medium-size spacesuit torso aboard. "But to stay on schedule with @Space_Station upgrades, it's safer & faster to change spacewalker assignments than reconfigure spacesuits."

"We do our best to anticipate the spacesuit sizes that each astronaut will need, based on the spacesuit size they wore in training on the ground, and in some cases astronauts train in multiple sizes," explained Brandi Dean, a spokesperson for NASA's Johnson Space Center.

"However, individuals' sizing needs may change when they are on orbit, in response to the changes living in microgravity can bring about in a body," the AFP quoted Dean as saying.

"In addition, no one training environment can fully simulate performing a spacewalk in microgravity, and an individual may find that their sizing preferences change in space," added Dean.

As a result of the rearrangement, Friday's spacewalk will be conducted by Koch and Hague as a female-male duo, during which they will continue the work to install powerful lithium-ion batteries for one pair of the station's solar arrays.

Meanwhile, McClain is now tentatively scheduled to perform her next spacewalk on April 8 with Canadian Space Agency astronaut David Saint-Jacques.