The Welsh Chamber Orchestra says it is facing a black hole in its accounts for the next year because of a row over funding from the assembly government.
The orchestra claims its funding is at risk "at the swipe of pen"
Last year, Culture Minister Alan Pugh announced a £400,000 support scheme was being extended until April 2006.
But the Arts Council for Wales has told the orchestra and six others that they must compete for next year's funding.
The assembly government said no guarantee was ever given over funding, which was now an arts council matter.
The Welsh Chamber Orchestra, which last year received £52,000 under the scheme, said its finances had been left in a "virtually impossible position".
In a letter to Mr Pugh, it said: "All our plans are suspended in mid-air, with no realistic opportunities of seeking alternative funding for a year that starts in three weeks' time.
Elinor Bennett, a member of the orchestra's board of directors, said her reaction was "great disappointment and real shock".
She said: "At a swipe of the pen, he has written off the funding and presumably given it to somewhere else.
"And told the seven chamber orchestras who had been making plans that the money is not there but they can apply for this money from the general pool, as it were, of the arts council.
ORCHESTRA FUNDING 2004
Sinfonia Cymru, Cardiff, £52,500
Welsh Chamber Orchestra, £52,500
Welsh Sinfonia, Cardiff, £22,500
Early Music Wales, south east Wales, £22,500
Chamber Orchestra of Wales, Swansea, £20,000
Ensemble Cymru, north west Wales, £15,500
St David Chamber Orchestra, south Wales, £14,500
"We know, of course, in the arts world, that the funding the arts council itself gets is quite overstretched."
Owen John Thomas AM, Plaid Cymru's culture spokesman, said he would be raising the issue at the culture committee's meeting in Newport on Wednesday.
He said: "Exactly a year ago today, we had a statement from the minister, through the arts council, stating that he will be providing funding for the next two years, quite clearly.
"These people were told they would be able to plan ahead.
"They've done that, they've organised events and now they're being told the money's not there, they have got to go in the queue and hope for the best."
The assembly government said when the Chamber Orchestra scheme was set up as a two-year funding scheme, it was always subject to the assembly government's planning round.
A spokesperson said: "When the funding offer letters were sent to the successful orchestras in 2004 it was made clear that the funding was only for 2004/5.
"Funding for 2005/6 was a matter for the arts council."