Ulster Unionist leader Sir Reg Empey has threatened to withdraw his officials from an important process which aims to create a system of schools for the future in Northern Ireland.
The Employment and Learning Minister issued the warning in response to information contained in a Sinn Fein briefing paper leaked to the UUP.
The Department of Education is remaining tight-lipped on the controversial briefing paper written by Sinn Fein Assembly staff and discussed at a party meeting of elected representatives and activists in Co Tyrone.
A department spokesman declined to comment on the Sinn Fein paper and also refused to respond when asked by the Belfast Telegraph whether the department had done any work on new 'admissions criteria guidance' being issued to schools.
Sir Reg said: "I have become increasingly concerned that the Executive has had no substantive discussion on proposed changes to our education system.
"Apart from statements from the Minister, there is no Executive position on what is for many the number one priority issue facing the Assembly.
"In March I agreed that the Department of Employment and Learning would participate in the area based planning process put forward by the Minister of Education.
"I did so after the Executive agreed to hold a special meeting to discuss education and we were also told that the Education Minister would supply a paper to the Executive.
"This meeting is still to take place. But the Sinn Fein paper released today shows clearly that area based planning is regarded by Sinn Fein as a mechanism to undermine those who hold a different view on academic selection to the Minister. This is what I feared all along.
"She is just intending to do her own thing and I am not prepared to lend my name to a process which is drifting us into what I believe is a disastrous situation for the future of our schools.
"Consequently, if the Executive does not quickly determine a joint position on education, I will withdraw Department of Employment and Learning officials from the area based planning process."
DUP education spokesman Sammy Wilson has suggested that grammar schools should only be allowed to accept pupils who reach a high academic standard - rather than continuing to fill to capacity at the expense of secondary schools.
UUP education spokesman Basil McCrea said: "Under the DUP's proposals, a third of grammar school places could be axed. This would lead to the destruction of the grammar school sector.
"If the number of pupils going to grammar schools is cut to just pupils achieving As and B1s, many grammar schools will be unable to survive unless they ask for financial contributions from parents or go all-ability to increase their intake.
"We could see a time when there could be as few as seven grammar schools in the whole of Northern Ireland if only the top academic pupils are given places.
"The Sinn Fein paper shows that the party intends to use the Department of Education's power with existing legislation to force schools to come into line.
"It also confirms that the DUP, whilst arguing for a limited amount of academic selection, are not wedded to the concept.
"Discussions need to take place within the Executive and the main priority for us is parental choice.
"Where parents want them, we should build additional grammar schools and there should be minimum standards for entry to make sure that pupils have basic reading and writing skills. We would also like to see massive resources going into the inner city secondary schools that are struggling."