SYDNEY/MELBOURNE (REUTERS, AFP) - Australia's Dreamworld theme park will permanently shut a water ride on which four people were killed last month, owner Ardent Leisure Group said on Wednesday (Nov 9).

Two women and two men died when rafts on the Thunder River Rapids ride at the hugely popular Dreamworld tourist attraction on the Gold Coast collided on Oct 25.

"Out of respect for the memories of Cindy Low, Roozbeh Araghi, Kate Goodchild and Luke Dorsett, and their deeply affected families, the ride will be permanently decommissioned," said Ardent's chief executive Deborah Thomas.

"The closure of the ride is the only respectful and appropriate course of action." She added that a permanent memorial was planned, with input from the families of the dead.

Police wrapped up their investigations earlier this week and handed back control of the park to management, but Dreamworld is yet to announce when it will reopen.

In the aftermath of the accident, the Australian Workers Union said it had voiced concerns about the operation and maintenance of some equipment at Dreamworld last year, while media reported alleged safety mishaps.

Dreamworld is conducting its own internal review of what went wrong and Tuesday announced a fully independent external probe of all its rides and operating systems by a mechanical engineering firm.

Management said it was also working with workplace health and safety officials and no ride would operate until all reviews were complete.

The park, Australia's biggest, has hosted 30 million people since opening in 1981 and last month's disaster was its first fatal accident.