Insolvent telecommunications company One.Tel Ltd has begun firing hundreds of workers as its outside administrator seeks to close down the company and discharge massive debts.
The Australian Community and Public Sector Union (CPSU) said an unknown number of staff at One.Tel's offices in Melbourne and Sydney were given redundancy notices early on Friday.
One.Tel employs 1,400 workers in Australia, and another 300 in its international operations.
"We are shocked and saddened at the announcement but the union is determined to pursue the issue of staff entitlements," a CPSU spokesman said.
Australia's fourth-largest telecommunications company, One.Tel provides mobile, fixed-line, broadband and internet services to 1.8 million customers in Australia, Hong Kong, the UK, France, Switzerland, Germany and The Netherlands.
One.Tel backers - including media magnates Rupert Murdoch and Kerry Packer - announced it was insolvent last week.
Steve Sherman, of corporate restructuring group Ferrier Hodgson, the company appointed to review One.Tel's financial affairs, said on Tuesday the company has 3,000 creditors and debts of more than Aus $600m (£250m).
It will be closed down within three weeks unless an investor throws a multimillion dollar lifeline to the failed company, he said.
The Australian Securities and Investments Commission (ASIC) is also investigating One.Tel to determine if the company kept operating without notifying regulators that it was insolvent, a violation of Australian corporate law.
Friday's sackings came amid reports that One.Tel founder and former director Jodee Rich has transferred millions of dollars in property to his wife to ensure he does not have to sell it if he is found personally liable for any of One.Tel's debts.