Russia's space agency says another attempt by its specialists to establish contact with an orbiting radio telescope has failed.

The Spektr-R satellite is continuing to transmit signals, but scientists have been unable to control the satellite since Friday.

Alexander Bloshenko, an adviser to the Roscosmos space agency, was quoted by the state news agency Tass as saying that Sunday's attempt to restore contact had failed. Another attempt is expected on Monday.

The was launched in 2011 and has exceeded its initially expected useful life of about three years. It is used to study radio sources within and outside Earth's galaxy.