When a shareholder took the microphone at the Nissan shareholders' meeting last week in Tokyo and spent 45 minutes hurling abuse and questions at the motor manufacturer's president, Mr Carlos Ghosn, in the low growl favoured by local tough guys, the 600-odd assembled knew they were witnessing a uniquely Japanese phenomenon that has all but disappeared from the public spotlight.

The tactics bore all the hallmarks of "sokaiya" - gangsters who threaten to disrupt shareholders' meetings unless they receive corporate payoffs.

The sokaiya sometimes extort money directly, but the standard method is to get companies to pay hefty subscriptions for useless two-page quarterly business publications, said Mr Harry Godfrey, managing director of Kroll Associates in Tokyo.

In his lengthy assault, the shareholder and other sokaiya attacked Mr Ghosn for his plan to slash the Nissan payroll by 16,000 and close five plants in Japan.

He berated the Brazilian-born executive for failing to bow as he entered the room, saying he wouldn't want to buy a car from a person so poorly versed in Japanese customs.

Mr Ghosn, who was sent by Renault to run the show after the French firm bought a 37 per cent stake in Nissan in what has been dubbed an alliance of the weak, was unfazed. He said he would do more to improve his understanding of Japanese etiquette.

The appearance of the mobsters to confront Nissan management was not totally unexpected. In the current poor economy, they focus on companies that are being restructured and are perceived as weaker and easier to intimidate.

They exploit the corporate Japanese desire for "quick, smooth, but short, meetings with no time for confrontation", said Mr Godfrey, whose firm provides anti-racketeer services.

But, the sokaiya do more than stamp their feet and make noise. What strikes fear into Japanese businesses and prompts them to cough up the cash is the gangsters' tactic of embarrassing executives in public with details of corporate dodgy dealing.

They typically dig up information on shady deals such as unsecured loans or lending to other gangsters, says Mr Godfrey.

But the sokaiya at the Nissan meeting did not mention shady deals. Instead, they focused on Nissan's three-year restructuring program and the massive job losses involved.

However, while the chief of a large Japanese company, bred on the culture of lifetime employment, may be embarrassed to be subjected to aggressive public questioning about such a plan, Mr Ghosn is a different corporate breed. With a reputation for a ruthless and autocratic management style, he simply shrugged off the criticism.

And that begs the question. Why did the sokaiya target a foreign-controlled company? It is widely accepted that foreign bosses don't tolerate payoffs to sokaiya.

"Old habits die hard. Maybe they thought this could work" reckons Mr Peter McKillop, vice-president at J.P. Morgan Securities Asia. Does this mean that the problem is back? "No," he said, "I don't think it's coming back. It never went away. Like any virus it's difficult to stamp out."

The trend, however, was away from this type of activity, he said.

Not everyone agrees. A business source familiar with the gangster problem said that companies which had stopped dealing with sokaiya in 1997 and 1998 were "back paying them again."

The source said that the sokaiya was most likely trying to make a name for himself at the Nissan meeting by waving the nationalist flag and "targeting the foreigner as an occupying force".

The sokaiya may have used the Nissan meeting simply as a platform to declare to the corporate world that they are back. After spending the last few years diversifying to make money by what Mr Godfrey terms, "traditional criminal methods", it would not be surprising if the gangsters were to yearn for a return to corporate intimidation. For it can be a very lucrative business.

Just how lucrative was shown in April of last year when 56year-old Ryuichi Koike, the king of Tokyo's sokaiya, was jailed for nine months for receiving illegal payoffs and loans worth around £80 million. In a scandal which prompted the suicide of an ex-chairman of the major Dai-Ichi Kangyo Bank (DKB), it was revealed that the bank and an affiliate had been making payoffs to gangsters, including Koike, for decades.

Other financial firms also made the payments, first made illegal in 1982, including Nomura Securities and three other leading brokerages. Indeed, the list of guilty businesses reads like a Who's Who of corporate Japan, and includes Nissan, Toyota, Kobe Steel, Japan Airlines, Mitsubishi Motors, Hitachi and many other big names.

For a lot of firms, the corruption spiralled out of control in the flush years of the late 1980s. As Mr Godfrey says: "During the bubble years, there were so many money-making schemes and not all of them were legitimate." With no shortage of filthy corporate laundry, especially in the financial world, that could be aired if payments were not forthcoming, the sokaiya had a field day.

Recent police figures, though naturally unreliable given the nature of the gangster business, indicate a firm downward trend. The National Police Agency sent 70 sokaiya-related cases to the prosecutors office in 1993, compared to nine last year. But the police say they do not yet consider the problem to be defeated.

And with Japan seeing a glimmer of economic revival in recent months, the sokaiya may be preparing for a return to the bubble years. Newspapers here recently carried allegations that gangster manipulation was behind a sharp rise and subsequent plunge in Japanese technology stocks, some of which are now trading at less than one-tenth their overvaluation of four months ago.

So is corporate racketeering back to plague Japan? Certainly the annual shareholders'meeting of more than 2,000 - mostly publicly listed - companies held yesterday were more lively than usual, although sources locally were reluctant to point the finger at the sokaiya.

The tactic of mass holding of meetings on the same day is designed to force the sokaiya to spread their resources thinly. Though it is within the law for the sokaiya, as shareholders, to disrupt meetings with verbal abuse and questions, 7,400 police were deployed to make sure they did not go beyond that.

According to Mr McKillop, changing economics leave Japan with no option but to crush the mobsters. "If Japan is globalising, deregulating and becoming more transparent, there is no room for sokaiya," he said.