The unprecedented move by the International Telecommunication Union (ITU) adds to pressure on Tehran as world powers consider a new round of UN sanctions over Iran's nuclear programme.

Iranian authorities have been jamming foreign satellite broadcasts into their territory since late last year, with the BBC and Deutsche Welle affected.

In a statement yesterday, ITU's radio regulations board said interference coming from Iran was harming signals from satellite networks run by Eutelsat, a French satellite operator.

Iran should find the source of the interference – which affects both radio and television signals – and "eliminate it as a matter of highest priority".

"In this case there is evidence that there is a deliberate attempt to block the satellite transmissions and so they are saying this should be stopped. This is prohibited under the regulations," ITU spokesman Sanjay Acharya said.