BBC Radio Cymru has been forced to change its playlists after losing the rights to thousands of Welsh-language songs in a dispute over royalty payments.
The BBC reports that 300 Welsh language artists were involved in the matter via collecting society body EOS, which called for a "fair price for Welsh music".
After EOS turned down an offer from the BBC, the station lost the ability to play 30,000 Welsh language songs from January 1.
Gwilym Morus, Eos chair, said: "It's a shame that the BBC have chosen to damage the national radio service because they are unwilling to pay a fair price for Welsh music.
"Regretfully I believe the BBC in London is showing a lack of respect towards their own staff in Wales and towards Welsh culture."
Playlist changes include a two-hour reduction in daily output with a later start of 6.30am and earlier finish at 11pm. Evening programmes showcasing new Welsh music have also been cut to an hour. Time will be filled with broadcasts of English language songs.
Sian Gwynedd, head of Welsh language programmes and services at BBC Cymru Wales, said: "While Welsh language music will continue to be the bedrock of our output, the current dispute will prevent us from playing most of our usual repertoire.
“This will clearly have a noticeable impact on the service we can deliver, but I would like to emphasise to our listeners that we are doing everything possible to protect the quality of our programming despite the difficult circumstances."
Following changes by PRS for Music in 2007 which affected their royalty payments, last year Welsh composers and artists set up EOS to deal with their licensing. The new agency acquired the rights for 331 Welsh acts from the PRS yesterday (January 1).
BBC National Trustee for Wales, Elan Closs Stephens said: "I understand the financial pressure on Welsh musicians but there are also huge financial pressures on the BBC, too, like all public bodies. Nobody wins from this action, least of all the Radio Cymru audience. I would urge you to continue in your efforts to ensure that this matter can be brought to a satisfactory conclusion."