The decision to set up the working party - made up of growers and representatives from producer organisations, the NFU, Defra and the RPA - was made after the industry called for more guidance on the scheme.
Pettitt said: "Following months of urgent meetings and time spent attempting to resolve issues with the scheme this year, the NFU found unanimous agreement and support from producer organisations for the creation of an experts' group to review producer organisation policy.
"The move by Defra to set up a producer organisation policy review group was welcomed by both producer organisations and the RPA. However, no sooner had this group formed and met than the current crisis unravelled. Given the continued concerns of the EU auditors, it's clear that the work of the review group is even more urgent if we are to get on an even keel with auditors and secure the future of the scheme.
"We are in contact with the RPA and Defra and are contacting ministers about this issue. Both the NFU president and I are working at the highest level to ensure the delayed payments are not prolonged further. This is an untenable situation for producer organisations and the issues bringing it about must be resolved without delay."
English Apples & Pears chief executive Adrian Barlow said a meeting of top fruit producer organisations had drawn up a list of ideas that it had passed on to the review group.
"It was felt there should be good discussions and sharing of experiences and concerns and values to identify the areas of great concern and to try to come up with some proposals that would be constructive in helping everyone overcome their differences," said Barlow. He added that growers spent the meeting going through the latest RPA document.
Phil Hudson, the NFU's chief horticulture adviser, told Grower that the working party meeting was a success and that the group will meet again on 7 December.
He said: "The producer organisations and all parties remain committed to securing rules that are equally understood by producer organisations and the RPA."
In a joint statement, Defra and the RPA said: "As we said in our statement to producer organisations, the issues raised by the EU auditors are serious for the industry and for UK taxpayers. We will be discussing these with ministers and we are aware they are a matter of priority. In those circumstances, it seemed to us sensible and proper to warn producer organisations that the RPA might not be able to meet its published target dates for payments."