Sunita Williams surpassed the record on Sunday

The record was set as she and a crewmate upgraded the International Space Station's cooling system on Sunday.

Ms Williams broke the previous record set by American Kathryn Thornton of just over 21 hours; setting a new one of 22 hours and 27 minutes.

With colleague Michael Lopez-Alegria, she completed the second of three

scheduled spacewalks in nine days.

During Sunday's spacewalk, which lasted more than seven hours, small amounts of toxic ammonia leaked from a fluid line.

The liquid ammonia, which freezes into flakes when it hits the vacuum of space, did not appear to touch either astronaut.

Contamination test

Mission Control told them to continue their task of hooking up ammonia fluid lines from a temporary cooling system to a permanent one.

Ammonia could cause respiratory problems for the three-person crew if enough of it got into the space station. Once the astronauts were back in the space station's airlock, mission controllers made them test for contamination. The test was negative.

Ms Williams was carrying out work on the ISS

Lopez-Alegria and Williams hooked up the permanent cooling system, covered an obsolete radiator that was retracted by remote control from the ground and stowed a fluid line that was connected to an ammonia reservoir.

They then moved on to other jobs ahead of schedule: removing a sun shade, photographing a solar array that will be retracted during space shuttle Atlantis' mission next month and making electrical connections for a new system that will allow power from the station to be shared with a docked shuttle.

The third spacewalk is set for Thursday, marking the first time three spacewalks will have been conducted in such a short period at the space station without a shuttle docked to it.

Lopez-Alegria plans to conduct a fourth spacewalk with Russian flight engineer Mikhail Tyurin on 22 February. After Sunday's spacewalk, Lopez-Alegria moved to third on the list of the most time spent spacewalking.

He is expected to surpass Jerry Ross's US record of more than 58 hours over nine spacewalks by the end of the month.