Campaigners say more direct action is planned as part of protests about the future of Welsh language TV channel S4C.
Cymdeithas yr Iaith Gymraeg, the Welsh Language Society, said BBC Wales and the UK government would be the targets.
From 2013, S4C will be funded from part of the BBC licence fee.
BBC Wales said the decision to change the funding arrangements were made by the UK government, and discussions were ongoing between the various parties.
Cymdeithas has accused BBC Wales of "betrayal" because of its "co-operation with the UK government".
Around 200 people demonstrated outside BBC Wales' Carmarthen office at the weekend.
Menna Machreth, Cymdeithas's media spokesperson, said: "The discussions at the moment are being held behind closed doors about the future of the channel and we think that is very undemocratic.
"They are ignoring the opinions of MPs who haven't even voted on these plans yet and ignoring the opinions of the Welsh Affairs Committee as well.
"So that's why it is so urgent that we're campaigning now."
S4C faces a 25% budget cut by 2015 under funding changes by Chancellor George Osborne.
A BBC Cymru Wales spokesman said: "The decision to change the funding arrangements for S4C was made by the UK government not the BBC.
"Discussions are ongoing between the UK government, S4C and the BBC and further details will be provided in due course."
BBC Director General Mark Thompson has agreed to meet with Cymdeithas within the next few weeks.
Last month, 20 people staged a sit-in at the lobby of BBC Wales' headquarters in Cardiff.