NASA has aborted a spacewalk outside the International Space Station because of a dangerous water leak in an astronaut's helmet, Belfast Telegraph said.

Italy's first spacewalker, Luca Parmitano, reported that he felt a lot of water on the back of his head barely an hour into the mission.

The leak was so bad that he needed help from a fellow astronaut getting back into the safety of the space station.

Parmitano at first thought it was sweat because of the exertion of performing routine cable work, but he was repeatedly assured it was not sweat. His spacewalking partner, American Christopher Cassidy, said it might be water from his drink bag. Cassidy said it looked like half a litre of water leaked out.

The water eventually got into Parmitano's eyes, prompting NASA to order the two men back inside. "It's a lot of water," said Parmitano once he was back in the air lock of the International Space Station.

The trouble cropped up about 90 minutes into what was to be a six-hour spacewalk to perform cable work and other routine maintenance. It was the astronauts' second spacewalk in eight days.

NASA rarely cuts a spacewalk short. It was the fastest end to a spacewalk since 2004 when Russian and American spacewalkers were ordered back in by Mission Control outside Moscow because of spacesuit trouble. That spacewalk lasted 14 minutes. This was the second spacewalk for Parmitano, 36, a former test pilot and Italian air force officer. He became the first Italian to conduct a spacewalk more than a month after moving into the space station.