A "TIGHT cash flow" has been blamed for United Dairy Power delaying its autumn and winter milk payments to suppliers.

UDP suppliers told The Weekly Times they were only informed about the delayed payments last Wednesday, the same day most of the suppliers were to be paid.

Many suppliers had already allocated the money - which they say ranged from less than $10,000 up to $65,000 - to crucial feed and fertiliser bills.

Most suppliers who spoke to The Weekly Times said they were disappointed with how the matter was handled and the UDP's lack of communication with suppliers.

"We are probably more annoyed at this stage there hasn't been a satisfactory justification for withholding our payment," one supplier said.

"The way it was handled, was pathetic," another said.

"There should have been a fax or email to all suppliers on the same day."

Other suppliers questioned future payments, saying the delay was not an isolated incident and was a blow to their confidence in milk prices.

UDP managing director Tony Esposito said the payment delay was a result of tight cash flow, a "lag" from last season.

Mr Esposito said the payments delayed averaged about $10,000-$15,000 and would be paid by Christmas.

"We keep a lot more at the farm gate to keep prices as high as possible, it has an affect on cash flow," he said.

"We pay as much as we can, to our detriment at times."

Mr Esposito said the delay in informing suppliers was because UDP staff waited for him to return from annual leave before informing him of the issue.

He said UDP preferred staff notify suppliers of the delay rather than them find out via a piece of paper.

He said the delayed payments affected less than 30 per cent of UDP suppliers as some suppliers, who produce more than 43 per cent of their milk during autumn and winter, have used their option to take the payment as it comes rather than wait for money later in the season.

Mr Esposito said no farmers had left UDP as a result of the delay.

He said UDP had spoken to affected farmers, who also had the option to speak to him directly if they required clarification.