Aged care providers have refused to negotiate with nurses on a new salary agreement until the Productivity Commission reviews the modern award, including the future of penalty rates.

The peak body for for-profit nursing home operators, Leading Age Services Australia NSW-ACT (LASA) has written to the NSW Nurses and Midwives' Association saying it will not enter into negotiations to renew the current enterprise agreement.

Brett Holmes, the general secretary of the NSW Nurses and Midwives' Association, said a standard agreement had been struck in 2010 and 2012 with LASA. The current agreement expires at the end of June this year.

"This is an attack on vulnerable workers who are looking after the most vulnerable people," Mr Holmes said.

"We fear these employers are being set up by their employer association to get a windfall out of the productivity commission outcome, which attacks rights including penalty rates ,which for some nurses make up to nearly 30 per cent of their take home pay.

"The productivity commission is due to report in November and the federal government said it will consider the Productivity Commission recommendations as their party policy".

Nurses were hoping to negotiate a new three-year agreement to begin in July.

A letter from LASA to the Nurses' Association says its members "confirm their intentions not to renegotiate the model agreement in 2015".

It said "the age service industry has undergone major reform which has had significant impacts on funding and financial arrangements. These reforms, in conjunction with other industrial proceedings, such as the Modern Award Review process and the Productivity Commission review of the Fair Work laws have created uncertainty and disruption for age service providers."

Although the terms and conditions of the current enterprise agreement will not change, nursing home operators have indicated they will seek agreement on a wage and allowance increase to take effect from July.

Mr Holmes said LASA's action would make aged care nurses vulnerable to changes to the Fair Work Act if the Abbott government  were to be re-elected.

"They are vulnerable to having their agreements set aside in the so-called public interest," Mr Holmes said, referring to a recent Fair Work Commission decision.

The controversial ruling allowed a Queensland transport operator to terminate a dozen enterprise agreements. This allowed employees to be employed under less generous conditions of the relevant award.

Mr Holmes said aged care nurses were paid from $21 to $22 per hour and mostly work part time.

Nursing assistants were paid an annual salary starting from $43,178 and registered nurses were paid between $52, 441 to $71,521.

"This means that thousands of vulnerable low-paid workers are being hung out to dry," Mr Holmes said. "They need the certainty of an enterprise agreement to provide stability around their employment to maintain their rights and not to be vulnerable to some political attack that may arise out of the productivity commission.

"LASA is the same employer association that was very keen to try and encourage their members to try to take the option of individual agreements.

"It is interesting that the not-for-profit operators are continuing to bargain."