A Russian scientist, Sergei Meshcheryakov, who warned that Soviet nuclear-powered satellites are presenting a serious danger in space, was arrested on Monday for treason.

A Moscow court remanded Meshcheryakov to house arrest on a treason charge punishable by 20 years in prison, according to state media reports.

Meshcheryakov worked at an affiliate of the Russian space agency Roscosmos, the Central Research Institute of Machine Building.

Details of the case have not been revealed.

State news agency, TASS, reported that two other employees of that institute have been arrested.

Meshcheryakov’s department head, Roman Kovalev, and a 75-year-old employee, Viktor Kudryavtsev

Kudryavtsev has been under arrest since July 2018 on an allegation that he passed secret information to a Belgian scientific organisation, the Von Karman Institute for Fluid Dynamics, with which the institute had been collaborating under a state agreement, TASS reported.