Thousands of students turned up for class in Australia today were locked out. Four bankrupt private colleges in Sydney and Melbourne closed overnight without notice.

Upset students crowded outside the college entrances in Melbourne and shouted for answers.

Global Campus Management Group, which owns the colleges, was put under voluntary administration on Thursday.

Australia's international student sector, worth about $12 billion, has come under fire after reports some colleges had taken payments for certificates and residency visas.