As a result, he is said to have made more then $40 million. But eventually his competitors caught up with him by having him tailed by an enquiry agent.

Such nefarious corporate activities rarely make it into print. But according to a recent survey of professional private eyes by BRW, it is increasing rapidly.

Corporate crime is booming and so is the business of private enquiry agents, who are being employed to debug offices, check up on business competitors, check patent infringements, check executive security, follow and investigate staff suspected of fraud, embezzlement or selling information to competitors, and to account for all the components of an acquisition.

But it does not stop there. Private enquiry agents say that companies are also bugging competitors, spying on them and attempting to buy information from employees. They are also tailing and photographing managing directors in their private lives, particularly looking for any evidence of sexual peccadillo's, which could provide a "negotiating edge" to a deal.

"They (some of Australia's top business people) have got a lot of dirt to hide, so they need the dirt on others. A lot are scrappers who made a heap of money and never thought that they would get in where they are now. They all have a lot of skeletons in the closet," says Frank Monte, the doyen of Australia's private investigators, from his plush mirrored and dusty pink suede wall papered office in Sydney's Australia Square.

Monte, whose own private life reads a bit like one of his investigations, has worked for a wide range of business people. His work for Aristotle Onassis in 1972, the Rockefeller family and the Dubai mercenaries are the topic for a book he is writing with the assistance of society writer Dorian Wild. Before no-fault divorce, his firm carried out 2700 divorce raids. Now he still trails, photos and bugs for couples in the throes of divorce for ammunition to fight for custody, maintenance and settlement.

Monte has ridden out of the changing fashions of corporate crime, surveillance, lie detection and, presently, debugging. He travels every year to the International Security Conference in New York to return in a few weeks' time with a laser bug, which can be aimed at a window half a mile away to pick up conversations.

Private investigators are of course cagey about other places they gather their information. The Privacy Committee is not happy with some of their sources, so they will all tell you all information is obtained legally and it is just not worthwhile approaching contacts in the Australian Taxation Office or the Police Department or the banks and finance houses.

When checking on some employees suspected of fraud, the private investigators admit to riffling through office drawers and diaries to undercover details. Sometimes they gather household rubbish to search for clues.

"Do you know what companies throw away? Whoever suspects anyone of coming around and collecting garbage? It is so simple but no one ever even thinks about it,"

It is not surprising, then, that society views private investigators with a degree of disdain, though the television image is one of excitement and romance. "We are neither a prostitute or a taxi-driver but somewhere in that region," says Monte, who plans to move to New York, where private investigators are an accepted profession.