Student applications from India, Vietnam and China has dropped 40 per cent last month following abrupt changes to Australia's visa regime, the country's top education agent has warned and asked the government to keep skilled migration route open for overseas pupils.

"Last month, there was a significant decline in applications from India, Vietnam and China. It's a concern," Tony Pollock, chief of country's leading international education and development organisation, IDP, said.

The drop has been attributed ever since overseas student attack crisis erupted that prompted government to tighten visa rules and forced many private colleges to shut down, according to "the Australian'.

Pollock warned a possible loss of AUD 600 million in export revenue due to decline in student applications.

Pollock said: "If there's a 10 per cent decline over a full year, with each student adding around AUD 30,000 to the economy, that would be AUD 600 million shortfall, conservatively."

"It's tougher to get a student visa, which means people are questioning whether they will ever get a (permanent) visa for Australia, and whether they should look elsewhere to get an education," Pollock said.

"Announcing suspensions of visa categories - even though they aren't student visa classes - and delaying the Skilled Occupation List doesn't help confidence," he said.

China and India are Australia's top two source countries.

Appreciating efforts to cleanse the industry, Pollock said government should keep the skilled migration pathway open for international students.

"Offering students the prospect of permanent residency - but only if they are sponsored by an employer - is a very uncertain outcome for those craving certainty," he said.

According to national statistics from Department of Education, Employment and Workplace Relations, there was an overall 40.8 per cent decline in Indian students beginning studies in universities, vocational education and intensive English language courses in January as well, compared with the same time last year.

Providers of English Language Intensive Courses for Overseas Students (ELICOS) - many of which are private collages - suffered the biggest hit nationally with an 88.6 per cent decline.

"While we are seeing nasty figures, the country as a whole is doing well and we should be back in growth in the Indian market in the next financial year" Pollock had said.