A senior Welsh MP and UK Government minister has launched a scathing personal attack on Welsh assembly Health Minister Jane Hutt.
Mr Howells' comments will annoy Hutt's supporters
In a letter obtained by BBC Wales, the Pontypridd MP Kim Howells questioned Ms Hutt's professionalism and criticised her record on the NHS.
Long NHS waiting lists mean the Welsh Assembly Government is often under attack, but criticisms from such close quarters are rare.
The assembly government has refused to comment on the letter.
Critics say the barbed comments of the UK transport minister show the frustration in Labour ranks at Westminster at the state of the health service in Wales.
Mr Howells complained that Jane Hutt took two-and-a-half months to respond to a letter he wrote on behalf of a constituent - and then fobbed him off with a reply from her diary secretary.
In his latest letter - his third to Ms Hutt's office - he said such behaviour did not suggest of a professional approach, and offered little encouragement to those who would like to contribute to the debate about how best to deliver improved health care provision in Wales.
Improvement, he says, was badly needed, and slow in coming.
Mr Howells - who represents a constituency with a high proportion of former miners - originally contacted Ms Hutt's office over concerns about the availability of liquid oxygen therapy for those suffering from lung diseases.
When he wrote, complaining about her delay in responding, he said :
"In the 15 years that I have served as an MP I have rarely, if ever, had to wait so long for a response from a minister of any description or any party.
"Never have I had to suffer the discourtesy of a reply on an important subject like this one, not from the minister, but from someone unknown signing it on behalf of the minister's diary secretary."
Mr Howells was also annoyed that Ms Hutt did not even choose to apologise.
"Such behaviour does not smack of a professional approach by your department and offers little encouragement to those of us, inside and outside of politics, who would like to contribute to the debate about how best to deliver improved health care provision in Wales.
"It is an improvement that is badly needed and slow in coming."
Hutt told an aide to respond to the query
Mr Howells went on to express his fury at failing to receive an adequate response to a matter raised by his constituents.
"The issue of liquid oxygen therapy is an extremely important one of the many people in Wales who suffer from lung diseases," he wrote.
"On the evidence of your response, I fear that it is not receiving the attention it warrants.
"I hope very much that you will consider improving the quality of the response of your department to ANYONE who might offer their co-operation on this or any other health care issue, let alone to a Labour minister in a Labour government that provides your department with extremely high levels of funding which we hope are being used to best effect."