An investigative panel has found no link to organised crime in the accounting scandal at Japan's Olympus Corp and has blamed two former executives for cooking its books over the past 13 years, Jiji news agency said on Tuesday.

Jiji, revealing the panel's findings just minutes before their scheduled release at 0600 GMT (1 a.m. ET), said former executive vice president Hisashi Mori and ex-internal auditor Hideo Yamada had crafted a scheme as long ago as 1998 to hide investment losses.

The Jiji report, which confirms a Reuters report on Monday, also said the concealment of losses amounted to 134.8 billion yen ($1.73 billion) at its peak, though the panel felt it would have been difficult for then auditor KPMG AZSA to spot.

Olympus, a maker of cameras and medical equipment, has lost half its market value since its sacked CEO, Englishman Michael Woodford, went public in mid-October with concerns over murky accounting and some expensive and questionable acquisitions.

But the stock jumped as much as 15 percent on Tuesday, extending a three-week rally fuelled by growing hopes that Olympus would not be delisted and that, instead, a few former executives would bear the brunt of any punishment.

I think the probability for Olympus to be kept as a listed company is pretty high right now and that's the market consensus, said analyst Nanako Imazu of CLSA.

Olympus must clear a series of hurdles to avoid being delisted, a humiliation that could force it into asset sales. The first of these challenges would be met if the panel were to find no involvement of organised crime in the scandal.

The panel's findings so far represent no major new surprise for investors, with Olympus having already admitted to hiding substantial investment losses for two decades and having named three former executives as the main wrongdoers.

Some doubts exist, however, about the ability of the panel to get to the bottom of such a complex and murky affair, which involves numerous, obscure counterparties and investment firms.

The panel has limited powers of investigation and was hired by the same board that sacked Woodford, who blew the whistle on the scandal immediately after he was fired as CEO in October.

I would have thought they didn't have the expertise to probe that (involvement by organised crime), said Jamie Allen, secretary-general of the Asian Corporate Governance Association, whose members include institutional investors that collectively manage assets of more than $10 trillion.

That's really a job for the police. So even if they say there's no evidence, obviously I don't think that's going to satisfy everybody because they'll want to know what the police come up with.

($1 = 77.8200 Japanese yen)

(Additional reporting by Mari Saito in Tokyo; Writing by Mark Bendeich; Editing by Richard Pullin and Ian Geoghegan)