Image caption The tank will be shipped to Kennedy Space Center, where the Columbia wreckage has been collected

Debris from the space shuttle Columbia, which burned up on re-entry in 2003, has turned up in a drought-stricken lake in eastern Texas.

The 1m-wide spherical tank was found in Lake Nacogdoches, near the Texas town of the same name where much of the debris initially fell.

The tank was part of the ill-fated orbiter's electrical power system and contained liquid hydrogen or oxygen.

A drought in the region has driven the lake's water levels down by nearly 3m.

A local policeman patrolling the area alerted authorities to the find.

"It had been out of the water for some time," Nacogdoches police sergeant Greg Sowell told the Associated Press. "It had been seen by local sportsmen... People didn't know what they were looking at."

Local authorities will arrange to ship the tank back to the Kennedy Space Center, where other Columbia wreckage has been collected for analysis. Nasa said about 40% of the orbiter had been recovered.

The Columbia shuttle broke up in the skies over eastern Texas in February 2003, killing all seven of its crew. The heat shield that protects the shuttle from the searing heat of re-entry was damaged on liftoff by a piece of insulating foam that broke away from an external fuel tank.