The level of paramilitary extortion rackets has increased in Northern Ireland since the Good Friday Agreement of 1998, a senior police analyst has claimed.
Small businesses are being forced to pay up to £10,000 a month to paramilitaries who threaten them with violence and intimidation, according to Bridget Lloyd, assistant director of analytical services at the PSNI.
Writing in the current edition of Economic Outlook And Business Review, Ms Lloyd said the sophistication of organised crime in Northern Ireland had been influenced significantly by paramilitary involvement.
In an article entitled Extortion - The Cost Of Doing Business In Northern Ireland?, she said: "It is hard to assess the scale and scope of this problem [extortion] in NI, as it is grossly underreported to police.
"What is clear is that extortion is prevalent in many parts of Northern Ireland and that its overall impact on businesses, individuals and on the community as a whole is significant."
She added: "Traditionally, demands were made on behalf of the organisation, very often under the guise of prisoners' welfare, but the release of most of the paramilitary prisoners following the Good Friday Agreement (GFA) has not led to any diminution in levels of extortion; if anything the problem has increased with individual members and former members operating independently but using their terrorist credentials to increase the fear factor for their victims.
"It is suggested they are operating with the knowledge of their leadership of their organisations on the understanding that they will not be afforded any organisational support if caught."
Ms Lloyd said extortion rackets often began with two or three individuals visiting a company and making an "invitation" to buy security services. New businesses will be asked for a one-off payment with subsequent regular monthly or weekly payments.
She said: "Typical demands are in the region of £50-£100 a month for small retail outlets, £1,000-£10,000 for small businesses and private individuals and there is no upper limit for demands of larger, often multinational, companies."
Ms Lloyd also said extortion rackets were run exclusively by men. No woman in Northern Ireland has ever been convicted of an extortion offence.
She said: "The vast majority of individuals convicted for extortion offences have previous convictions for other types of crime; a large proportion of extortionists have a tendency to violent crime and lawlessness. "
The police analyst said the local building trade was the worst afffected by extortion, although fast-food outlets, restaurants and licensed premises, car dealerships and other retail outlets had also been targeted.
She said: "The impact on the victim is immeasurable. Any financial loss is often the least of the victim's worries.
"If the victim decides to pay, he will continue to live with the fear of physical violence for himself and his family and damage to his property.
"Moreover, he must endeavour to raise the money demanded to make his regular payments - this loss of earnings must then be recouped in other ways€ a shop owner may have to increase his prices slightly."
Ms Lloyd said a survey of the construction industry conducted in 2005 had shown that 48% of respondents said they had been victims of extortion but 96% of them had not reported the offence to police.
The PSNI Extortion Unit launched an extortion helpline in May this year.
The number is (028) 9092 2267.