Stormont's education minister should focus on educational underachievement rather than academic selection, Sinn Fein has insisted.
Sinn Fein chair of the Assembly's education committee Barry McElduff was reacting to Peter Weir's efforts to find a common post-primary transfer test.
There are currently two unregulated tests used by grammar schools still selecting on the grounds of academic ability in Northern Ireland.
DUP minister Mr Weir has acknowledged the ideological differences between his party and Sinn Fein render it impossible to reach political consensus on reintroducing a state transfer test.
However, the minister is trying to encourage the bodies that run the two unregulated tests - the Association of Quality Education (AQE) and the Post-Primary Transfer Consortium (PPTC) - to find an agreed format so children do not have to undergo multiple exams.
At present children attempting both tests have to sit five separate exams.
Mr Weir informed his scrutiny committee of his intention earlier in October and he has now appointed an academic expert - Professor Peter Tymms, from the School of Education at Durham University - to mediate between the bodies to see if a common test can be delivered by next autumn.
Mr McElduff questioned the minister's priorities.
"Rather than reinforcing academic selection, the minister needs to address the issue of educational underachievement," he said.
"Academic selection is not the way forward.
"There is a whole body of educational research and evidence that demonstrates that academic selection is one of the contributors to poor educational outcomes and also leads to social divisions.
"Under Sinn Fein ministers over the past decade we have seen year-on-year improvements in achievement and attainment levels.
"The Education Committee has just finalised the terms of reference for a Committee Inquiry that will run throughout 2017 that will focus on educational underachievement, including an examination of the role academic selection might play.
"Sinn Fein will continue to express our opposition to tests at the age of 10-and-a-half and 11 years of age."
DUP member of the education committee Carla Lockhart said the minister had taken the right approach.
"Retention of academic selection was a manifesto commitment put forward by the DUP and I am pleased that we are delivering on this," she said.
"To have a system of academic selection in which there is more than one test isn't sustainable in the longer term.
"It creates pressure on teachers to provide help and support and not least parents and pupils. A resolution to single transfer impasse will be best for our children.
"We need to create a system which gives equality to all in the education system. At present, we have multiple transfer tests which creates ambiguity in grading as well as extra tests for those who chose to sit both.
"I welcome the Minister's action on this issue. The Minister for Education is willing to listen to concerns and will act on them. This is another example of the DUP listening to the public and implementing their wishes."
In September, Mr Weir granted permission for primary schools to use school time to prepare pupils to sit the tests. Previous Sinn Fein minister John O'Dowd had opposed such preparatory work.