Hanlong won Sundance over with a sweetened 57 cents-per-share offer last week but the takeover cannot proceed without regulatory approval which is said to be waiting on an anti-trust probe into the Chinese firm.

Australia's Securities and Investments Commission (ASIC) is investigating three former Hanlong executives for insider trading related to the Sundance deal and a takeover bid for uranium explorer Bannerman Resources.

Requesting a trading halt to clarify the situation, Sundance said the Chinese firm had assured it that it was "continuing to work productively" with Australia's foreign investments board (FIRB) and was on track.

"(Hanlong) expects to receive FIRB's decision well within the indicative timetable," Sundance said in a statement to the Australian Stock Exchange.

"Hanlong has informed Sundance that ASIC's investigation focuses on the individuals, not Hanlong," it added.

Sundance said Hanlong was required to inform it of "any material development that may lead to the non-fulfilment of regulatory approval" and it had advised there was "no reason to provide such notification."

As well as ASIC and the FIRB, Hanlong must get approval from China's National Development and Reform Commission and secure approved financing.

Hanlong vice-president Calvin Zhu, director Steven Hui Xiao and employee Fan Zhang had their assets frozen and were banned from leaving Australia under a Supreme Court order sought by ASIC.

Xiao's wife Xike Hu, another woman, FanFan Chen and a company associated with Zhang, Wingatta Pty Ltd, also had their assets frozen over the insider trading probe.