International students will be tested on their grasp of the English language under a scheme to be introduced in 2018.

Education Minister Simon Birmingham will tell an education conference in Hobart on Thursday the government will introduce new English language standards for students in 2018.

English Language Intensive Courses for Overseas Students will have to formally assess students where they provide direct entry to a tertiary course.

At the moment, students can pass a course without proof and then start university studies.

Senator Birmingham says the government doesn't know exactly how many of the 150,000 ELICOS students last year weren't up to scratch, although the vast majority achieved high-quality outcomes.

"But we know there are a number of anecdotal instances, that you hear of students not being able to fully participate in group work or struggling through the class work that is set for them," he told ABC radio on Thursday.

"It is essential for those international students and for the domestic students who they ultimately study alongside in our universities, TAFEs or other education providers that they have the English language skills to succeed."

The standards will be extended for the first time beyond universities to vocational education and training courses.

All ELICOS courses will have a minimum of 20 face-to-face contact hours per week and a maximum teacher-to-student ratio of 1:18.

Of those who studied the English-language courses in Australia last year, more than 60,000 went on to further study, mainly in higher education or vocational courses.

Senator Birmingham says the changes will strengthen Australia's reputation as a high-quality destination for international education, a sector worth $28 billion a year.

The clearer, stronger standards would also make it easier for higher education regulator TEQSA to weed out providers doing the wrong thing.