Low-scoring school students would be all-but barred from becoming teachers under a Labor government, in a bid to improve results in the classroom.

Key points: Tanya Plibersek says Labor plans to restrict entry to the top 30 per cent of students

Tanya Plibersek says Labor plans to restrict entry to the top 30 per cent of students Universities have allowed students with ATARs below 20 into teaching courses

Universities have allowed students with ATARs below 20 into teaching courses Students will still be able to access bonus point and alternative entry pathways under the plan

Universities have been criticised for letting low-scoring students — some with ATARs below 20 — into education courses over recent years.

Labor has vowed to restrict entry to the top 30 per cent of students if the sector does not take action sooner.

"Labor wants the best and brightest Australians studying teaching," education spokeswoman Tanya Plibersek said.

"If universities don't do the right thing and fix this themselves, a Labor government will make them."

ATAR is short for Australian Tertiary Admission Rank.

Universities have increasingly supplemented ATARs with bonus points, such as those awarded to students from certain geographic areas, helping some with very low ATARs meet the published cut-off for teaching degrees.

The ABC has previously revealed that students who scored in the bottom 50 per cent of school leavers made up half of all those offered places in teaching degrees in NSW and the ACT in 2015.

There were 28 offers made to students scoring an ATAR of 0-19, 29 offers to those scoring 20-29, and 73 offers to students with an ATAR of 30-39.

"We want young Australians with a track record of achievement, motivation and capability to teach the next generation," Ms Plibersek said.

"We want a career in teaching to be a first choice, not a fall-back."

Unless universities "quickly" lifted entry requirements towards an ATAR of about 80, a Labor government would cap places in teaching degrees — a move that would effectively increase the minimum entry score.

Students would still be able to access bonus point schemes and alternative entry pathways under the plan.

Universities Australia's chief executive Catriona Jackson urged caution, suggesting the policy could have unintended consequences.

"We would urge the Opposition to consider a range of policy approaches to encouraging young Australians into the teaching profession," Ms Jackson said.

"Decision makers should be careful not to see the ATAR as the only way to measure the capability of prospective students.

"Universities use a number of diverse ways to assess a student's ability to succeed."

New South Wales and Victoria have already taken steps to improve the quality of students entering teaching degrees and entering the classroom.