Sometimes it's hard to feel sorry for the rich. Like when Umbro complains that kids are wearing knock-off Manchester United shirts, bought on the street for £15 instead of £50 in the superstore.

Then comes a news report from abroad - 300 infants die from using counterfeit baby milk powder - and the balance of public opinion shifts swiftly and firmly against those responsible.

But the economics is more straightforward; trade mark piracy has trebled in the past decade and now represents somewhere between 3 per cent and 6 per cent of world trade. According to the International Anti-Counterfeiting Coalition, knock-off goods cost US companies alone around $200 billion (£142 billion)a year.

And the Republic's new-found wealth and brand-awareness, combined with a traditional ambiguity towards authority, is creating a fertile market for counterfeit goods.

Last week, the Revenue Commissioners put on display around £250,000 worth of knockoff designer sport and leisure wear. The two tonnes of clothing was seized by Customs officers in just five raids; they found sportswear branded Lacoste, Adidas, Nike, Umbro, Fila and Reebok, as well as clothes marked Levis and Tommy.

Clothing manufacturers and the authorities say what gets captured is merely the tip of the iceberg.

"These products are very visible. You only have to walk down Henry Street in Dublin or visit a country fair to see them," said Mr Jim Grant, manager of the Revenue Commissioners' Customs and Excise investigation bureau, displaying the latest hauls.

Mr Garret Breen of A & L Goodbody's intellectual property unit says that while the Garda and the Customs and Excise have stepped up their efforts, the volume of illicit imports is accelerating.

"As other countries in Europe have been successful in fighting this thing, so manufacturers have moved on to us," he says.

Legitimate businesses are becoming increasingly irritated by what they see as the brazen nature of the street sellers. "It creates a bad image if things can be sold as openly and as illegally as that," says Mr Ed McDonald of the Henry Street-Mary Street Partnership. "It does have an effect on the sale of legitimately-sold goods - people pay good money for branded goods and they deserve the full value from that."

Another concern for the legitimate retailers is that while in the past most counterfeit goods were of poor quality, some are now the equal of the original articles.

Occasionally, the counterfeit goods are actually made in the same factory as the originals, with the contract manufacturer simply doing an unauthorised run-off for back-door sales.

To some consumers, buying one of these articles might seem like victimless crime - it's exactly the same piece of clothing, except that there's no need to pay an inflated price for the label. The Revenue Commissioners take a different view; they say it is taking money from the State.

"From a Revenue point of view there are several issues," a spokeswoman says. "First of all there is no duty paid on the clothes being imported; also, there is no VAT paid on the goods; and lastly there is no employment or income tax paid by the sellers."

Many within the retail community add that there is not much of a financial disincentive being handed down by the courts when sellers of pirated goods are caught.

"It takes a year to get to court, and then the court typically hands out fines of between £50 and £100," says Mr McDonald.

"Now, certainly, the idea is to find the supplier, but £50 for a seller of counterfeit goods is a derisory fine. And if the level of fine is as low as that, a lot of people will take the chance."

Another risk attached to fake goods lies with the buyer, especially for goods other than clothes and shoes. Although apparently less prevalent in Ireland, some countries have a growing problem with pharmaceutical and chemical fakes. In Vietnam, 300 children died last year from using counterfeit baby powder, 100 people died from a poisonous, falsely-labelled liquor and 27 people died from fake medicine.

Car and truck brake shoes and linings are regularly copied; one batch found by the Nigerian authorities took 10 times the distance to stop a vehicle as the real thing.

In Britain, counterfeit bus brake diaphragms burst after a short time, making the brakes of vehicles innoperative. Aircraft brake parts, also found in Britain, were made from mild rather than tempered steel.

In the US, counterfeit helicopter parts caused several accidents while nuts and bolts used to build apartment blocks caused buildings to collapse during an earthquake.

In Canada, copied industrial hoists were missing a vital safety brake and could have caused serious injury.

In the Middle East, fake electric sockets were not properly insulated and caused fires and electrocutions.

Just last month, hundreds of Italian men travelled to the tiny republic of San Marino, one of the few European states where the anti-impotence drug Viagra is legal. But many wound up buying a counterfeit product, made entirely from ordinary vitamin substitute formula.