A corruption probe into long-forgotten defence contracts has given authorities in Greece a small financial victory, along with the promise of revelations into decade-old graft.

The sum of over 9.0 million euros ($12.3 million dollars) has been handed over to the state by Antonis Kantas, a former defence ministry official turned state witness.

Kantas, 72, was a deputy procurement director at the defence ministry from 1997 to 2002.

He has admitted pocketing over 10 million euros from kickbacks related to the purchase of submarines, rockets, fighter aircraft and tanks.

"I took so many bribes that I cannot remember them all," Kantas said in his testimony, according to press reports.

Kantas had served under socialist defence minister Akis Tsochatzopoulos, 73, who was jailed in October for money laundering.

That 20-year prison sentence has loosened tongues after years of silence.

Kantas was originally arrested in September, but the bulk of his testimony began pouring out last week.

He has since named about a dozen other suspects, most of them businessmen and weapons intermediaries, but justice officials are hoping to net bigger fish among the Greek political elite.

"We are determined, any hint of corruption will be investigated to the end," government spokesman Simos Kedikoglou said on Friday.

A decade earlier, a parliamentary committee had found insufficient evidence to indict Tsochatzopoulos over the suspect purchase of Russian Tor-M1 anti-aircraft missiles.

Kedikoglou had been a member of that committee, and noted on Friday that lawmakers at the time had been frustrated by the lack of evidence against the former minister.

"It was an awful feeling, to understand that something is wrong but to not be able to prove it," Kedikoglou told SKAI Radio.

"We had very little access to documents. We had very little evidence," he said.

A justice source told AFP this week that "there are hundreds of millions of euros and dollars from procurement programmes spread out in accounts around the world."

"It takes time to open these accounts because intermediaries and offshore companies are involved. It is certain that politicians are behind such cases, and witnesses are covering up for them," the source added.

The investigation however still faces major hurdles.

One of the new suspects named by Kantas is an 83-year-old ailing businessman who nearly collapsed during testimony.

Another suspect claims to suffer from amnesia.

The case has dominated headlines in a country suffering from four years of straight austerity cuts and trying to recover from a six-year recession.

This particular case occurred at a time when Greece was spending millions of euros on weapons in a costly arms race with neighbouring Turkey.

To placate public anger, the finance ministry this week said the money returned by Kantas would be diverted to health and education, which have sustained major budget cuts in recent years.

However, many in the country doubt that endemic corruption in public office will be eradicated as a result of the investigation.

Also this week, the chairman of Greece's main children's hospital was arrested after he was taped allegedly accepting a 25,000-euro bribe.

"Did the bribe tsunami described by Kantas cease after his departure? Or is it still ongoing?" main opposition party Syriza said in a statement.

The case is bad news for the conservative-socialist coalition government ahead of local elections in May.

The conservatives and socialists have ruled Greece for the past 40 years, and are considered responsible for its financial and corruption ills.