The Welsh Assembly Government has expressed concern about a deal which is expected to see the BBC take over the funding of Welsh language channel S4C.
Culture minister Alun Ffred Jones also expressed his surprise and anger at not being informed about the move.
S4C's governing body will meet later to consider its response.
It is unclear if the BBC will have to fund the entire £100m budget, but there are assurances the channel would stay operationally independent.
Under the arrangements, it is being reported that the BBC would take over the finances of S4C by 2015.
Government sources have said there is no question of the BBC "taking over" S4C.
News of the arrangement leaked on Tuesday ahead of the spending review appears to have suprised both politicians and broadcasters.
Culture minister Alun Ffred Jones told BBC Wales that there had been no discussion or debate at all in Wales about the new funding arrangements for S4C.
He said the move had gone under the radar and that the channel was being dismantled with no reference to Wales at all.
Mr Jones said: "I knew nothing of a deal."
He also denied that there had been any discussion of transferring S4C to assembly government.
"You are talking to me because precisely this is a story about the BBC taking over effective financial control of S4C, and whoever holds the purse calls the tune.
"Now this is very worrying. We have to await the details and obviously look at them carefully.
"It is not healthy, it doesn't matter what the BBC is about, it is not healthy to have one broadcaster dominating the broadcasting and the media scene here in Wales.
"And therefore we will have to look carefully at how to preserve the independence of S4C if that is possible within the parameters of the deal".
The minister said there was also concern about the BBC's domination of broadcasting in Wales.
"Not that the BBC's bad or doesn't do the job well, it just over dominates the scene.
"But in terms of editorial control then it is very important that we have another body that actually commissions programmes apart from the BBC.
"It is simply not heallty to have one organisation overbearingly influential in this field."
BBC Wales political editor Betsan Powys understands that a model being proposed is a joint management board to govern the relationship between the BBC and S4C.
"However, this would also need to satisfy the Department for Culture, Media and Sport's (DCMS) requirement for S4C to have operational independence from the BBC - a tricky line to walk," she said.
Shadow Wales Office Minister Owen Smith MP said he feared the impact of the BBC taking control of S4C would be two fold:
"One it will impact on the plurality of broadcasting in Wales and we will see a dimunution of that plurality.
"Secondly, it's effectively a budget cut for the BBC. They're already talking about the BBC's budget being cut by almost 20%, 16 to 17% over that period, that's a fifth of the BBC budget by my reckoning, that's pretty enormous.
"Is this £75m which S4C is going to cost going to come out of BBC Wales budget? I sincerely hope not, I hope it will be spread more evenly. Either way, it's a very big slice of money."
Education Secretary Michael Gove told BBC Wales that funding for S4C would come out of the "very very generous settlement that the BBC has had over the years."
'Devil was in the detail'
"The BBC has already, thanks to Mark Thompson, been saying to some of the people who've been earning more than £200,000 to £300,000 that their jobs will have to go.
"And the BBC is leading the way in saying to some of the highly-paid executives who've been essentially using public money to fund their very generous salaries that in the future they need to have their money go to ensure that S4C, which does a very good job, is sustained in the future
S4C chairman John Walter Jones was briefed by Culture Secretary Jeremy Hunt about the changes on Tuesday.
Members of the S4C executive and authority are expected to meet later to consider their response.
Plaid's parliamentary leader Elfyn Llwyd MP said there were a lot of questions to be asked and the "devil was in the detail".
It is believed the BBC will also have to fund the World Service, but the licence fee will stay the same for six years, under the arrangements.
Media commentator Jon Gower told BBC Radio Wales: "There's clearly been a lot of horse-trading.
"The speculation is that the BBC in order not to take a big hit on its licence fee - having to give free licences to older people for instance, over 75s and so on - has actually decided to embrace conceivably not just the cost of running S4C but also the World Service."
Rhys Llwyd, vice chair of the Welsh Language Society, Cymdeithas yr Iaith Gymraeg, said the news was "unbelievable".
He added: "The Tories and Liberal Democrats have lost the plot and haven't thought this through."
Last week, Culture Secretary Jeremy Hunt signalled he wanted to break S4C's funding link with inflation, saying it was "unsustainable".
The DCMS has already asked S4C to draw up a response to budget cuts of either 25% or 40%.
S4C said cuts of 40% to its £100m budget would prevent it fulfilling its legal duty to provide high quality and diverse programming.
BBC Wales and S4C have also they would look at collaboration, and in the long term, possibly sharing a single media centre.