Following three reports of riders falling off because of a power problem, all Segway scooters were recalled on Friday for a software upgrade.

One of those who fell down sustained head injuries that needed stitches, the US Consumer Product Safety Commission and the company said in a joint statement.

Some Segways may not deliver enough power, especially when the batteries are running out, the statement, posted on the Internet, said.

"We have very high confidence in the safety of the Segway HT and this software upgrade further enhances the safety margins of the machine," the company said in a statement.

The Segway carries one person who stands on a small platform between two wheels. Leaning slightly forward moves the scooter forward, leaning back makes it reverse course.

The transporter was invented by investor Dean Kamen.