The Australian navy has commissioned the MU90 torpedo after successful testing firing in August, but years of delay.

All the navy's ANZAC and FFG class frigates now have the lightweight MU90, an anti-submarine torpedo that operates in shallow waters, including in congested areas.

It can be fired from ships or aircraft and has a range of between 7.7 miles and 15.5 miles depending on speed, which can be more than 50 knots.

In August, the Department of Defense confirmed that the ANZAC Class frigate HMAS Stuart fired an explosive warhead against a specially designed target in the East Australian Exercise Area.

The MU90 was developed by EuroTorp, a consortium of French and Italian defense businesses set up in 1993 specifically to design and build lightweight torpedoes. EuroTorp consists of Thales, the Finmeccanica company of Whitehead Alenia Sistemi Subacquei and DCNS -- Direction Technique des Constructions Navales.

The torpedo is in service with the navies of France, Italy, Germany, Denmark and Poland.

"The MU90 is a significant addition to the Australian navy's anti-submarine warfare capability," Thales Australia Chief Executive Officer Chris Jenkins said."This is particularly important given the strategic significance of our maritime operational environment."

The MU90 has had a difficult entry to service, The Age newspaper reported in August, after the test firing.

In 1997, the navy began searching for a torpedo to replace 1970s-era Mark 46 torpedoes.

The MU90 weighs 660 lbs. In comparison, the Mark 48 heavyweight torpedo aboard Australia's Collins submarines weighs 1.5 tons.

In 1999, the Ministry of Defense chose the MU-90, believing it to be a low risk "off-the-shelf" acquisition, The Age report said.

The $639 million project experienced major technical problems and ran years late, going onto the government's projects-of-concern list.

In May 20011, a report by the Auditor General blasted the Department of Defense for badly managing the torpedo purchase which, even though signed in 1998, had no firm delivery date.

"Planning and management was inadequate,'' the Auditor General said.

There had been ''an underestimation of ... risk,'' even though almost $400 million has been spent.

The project ''won't deliver the capability originally sought by the Australian Defense Force, with uncertainty surrounding what will be delivered."

The audit report said the government knew so little about the torpedo when the decision was made to buy it, that officials ''believed the MU90 to be an off-the-shelf acquisition ... already in service with the other navies. This was not the case.''

The test firing in August proved the project was back on track and nearing completion, Warren King, Chief Executive Officer of the Defense Materiel Organization, said at the time.

"Delivery of this important defense capability is due to the combined and concerted efforts of DMO, navy and defense industry to remediate the MU90 lightweight torpedo replacement which was removed from the projects-of-concern list in November 2012," King said.