The Department of Education (DENI) has denied claims by an SDLP MLA that 80% of pupils are not taking up online classes during the Covid-19 crisis.
Following a meeting of Stormont's Education Committee on Wednesday, West Tyrone MLA Daniel McCrossan said that officials had "confirmed" that 240,000 of Northern Ireland's 340,000 students are not using online resources.
However, a DENI spokesperson responded by saying that it "does not agree" with Mr McCrossan's interpretation of the figures.
Schools have been closed for five weeks since the start of the coronavirus lockdown, with many teachers delivering sessions through online apps and websites such as Google Classroom and Zoom.
However, concerns have been raised that many young people are missing out as they do not have access to devices or broadband.
DENI has sent principals a questionnaire to find out how successful online learning has been.
Mr McCrossan said it was "hugely worrying" that students in Northern Ireland have not engaged with online classes since schools closed their doors.
"Not only could this impact on educational outcomes and exams, but it also calls into question whether other means of teaching students have been successfully deployed," he added.
"The root causes of this problem need to be investigated immediately.
"I have written to the minister (Peter Weir) requesting that his department review this issue immediately and propose recommendations.
"This could have a hugely detrimental impact on students should online classes be inaccessible for many."
In response, a spokesperson for the department said that its officials had not confirmed the figures that Mr McCrossan had used.
"Secondly, Mr McCrossan would appear to believe that nursery and pre-school children should be engaging daily in online classes as he has included them in the total number he quotes," the spokesperson continued.
"Thirdly, the figures presented show daily snapshots of some aspects of online learning activity, but they do not reflect the totality of such activity, nor would anyone expect all learners to be engaging in online lessons every day."
The department also said that the figures which were quoted related to one of a range of metrics provided by the Education Authority's C2K system, indicating use of the applications they are able to track.
"It is therefore not reflective of the entire access to online learning being made by our schools," the spokesperson said.
"The Education Authority's C2K system has seen a significant increase in online learning activity since schools have closed.
"Pupils also have access to multiple other online learning resources outside of those which can be monitored by C2K, for example, BBC learning websites.
They added: "Additionally, a range of other educational software providers have also made their resources available free during this crisis and schools in Northern Ireland can avail of these online tools.
"Many schools are also making hard copy resources and learning materials available to their pupils."