Russia launched checks Tuesday after its space chief said an air leak on the International Space Station last week could have been caused by deliberate sabotage.
Space agency chief Dmitry Rogozin said the hole detected Thursday in a Russian space craft docked at the orbiting station was caused by a drill and could have been done deliberately, either back on Earth or in space.
Astronauts used tape to seal the leak after it caused a small loss of pressure that was not life-threatening.
"There were several attempts at drilling," Rogozin said late Monday in televised comments.
He added that the drill appeared to have been held by a "wavering hand." "What is this: a production defect or some premeditated actions?" he asked.
"We are checking the Earth version. But there is another version that we do not rule out: deliberate interference in space."