Education Minister Jane Davidson has denied misleading voters over the cost of Labour's pre-election pledge to give free breakfasts to Welsh primary schoolchildren.
The free breakfast scheme is currently being trialled
Newly-released figures have revealed that initial estimates prior to the 2003 assembly elections calculated that the scheme would cost £16m a year.
But latest figures predict it could cost around £40m annually.
Ms Davidson said Labour was still committed to delivering the policy.
Figures released by the Welsh Assembly Government showed that initial calculations had been based on only 11% of pupils taking up the scheme.
This led to accusations by the Western Mail newspaper that the Labour party had misled voters into thinking the policy was "fully-costed" and "thought-through".
Speaking to BBC Wales' Dragon's Eye programme, Ms Davidson denied this, and said the figure of 11% had come from the take-up in pilot schemes in England.
And she dismissed concerns that one senior figure had described his calculations, made shortly after the election, as "only back of the envelope calculations at best".
"We are breaking new ground with this so of course we didn't have ready-made figures," said Ms Davidson.
"We did have worst-case scenario figures. And we looked at those and considered the policy was worth doing.
"The info we have available as of the pilots at this point is the cost of the project, with 100% take-up, would be in the reach of £40m."
Jane Davidson has denied misleading voters
However, she did admit that the pre-election pledge was "in a sense...always a shorthand" and it was up to individual schools to decide if they wanted to participate.
But Ms Davidson did stress Labour had always intended the breakfasts to be available to all primary school children.
"If you go back to our pledge, we have always been very, very clear," she said.
"We want to make breakfasts available to all children in primary schools who want it.
"We are as consistent about our commitment as we have always been and we want as many children as possible to participate in this."
The figures were released by the assembly government after a request in line with the Freedom of Information Act.
The scheme is currently being trialled in 48 primary schools, but will soon be available to all 1,600 primary schools in Wales.