The growth of illegal file-sharing could cost European countries 1.2m jobs and 240bn euros (£215bn) by 2015, an industry report claims.
The study, commissioned by an industry body and endorsed by trade unions, studied the impact of web piracy in Germany, UK, France, Italy and Spain.
It claims that without measures to curb piracy, the UK alone could lose up a quarter of a million jobs by 2015.
But campaigners described the report as "corporate propaganda".
'Need for action'
The study, conducted by economics firm TERA Consultants on behalf of the International Chamber of Commerce, said that the UK's creative industries experienced losses of 1.4bn euros in 2008 because of piracy.
Brendan Barber, General Secretary of the TUC, said that the results showed piracy was a "major threat to the creative industries in terms of loss of employment and revenues".
"If there was ever the proof needed to demonstrate why the Digital Economy Bill is imperative for the protection of our creative industries, this report is it," he said.
The Digital Economy Bill was outlined in the Queen's speech in November 2009.
It includes various proposals to tackle illegal file-sharing including a so-called "three strikes" element, which would see persistent pirates cut off from the net.
It also includes element that would give courts the power to block websites that facilitate copyright infringement.
The bill has been passed by the Lords and is now expected to be rushed through the Commons before the general election.
There has been a groundswell of opposition to the Bill from firms such as British Telecom, Google and Facebook, which say that elements of the bill could undermine free speech on the net without reducing copyright infringement.
A campaign has also started on the internet encouraging people to write to their MP to stop the government rushing the bill through "without proper debate"
Jim Killock of the Open Rights Group (ORG) is a vocal opponent of the Digital Economy Bill and the new research.
"I am fed up of hearing corporate propaganda being deployed in order to justify intrusions on our rights to freedom of speech, privacy and to a fair trial," he said.
"We have no truck with infringement of copyright, but it is shameful that anyone from the Labour movement can attempt to justify removal of vital services such as the internet as a punishment."
The ORG recently revealed that certain amendments to the bill proposed in the House of Lords - but not passed - had been drafted by music industry group the BPI.
"Members of the Labour movement spent decades fighting for people's rights to basic services, education, and political organisation: they need to ask themselves where their true values lie," said Mr Killock.
"Are they with Gordon Brown's call to recognise the internet as just as vital for the today's citizens as water, gas and electricity; or are they with music industry lobbyists, calling on Parliament to infringe people's human rights?"
The new report used data from EU countries, the World Intellectual Property Organization and Eurostat, the EU's statistical gathering arm.
It said its figures were a worst case scenario based on consumer Web traffic growing 24 per cent annually.
The report said that European creative industries generated 860bn euros and employed 14.4m million people in 2008. In the same year it estimates that 10bn euros and 186,000 jobs were lost across Europe.
Extrapolating that data, it suggests that up to 1.2 million jobs and 240 billion euros worth of European commerce could be wiped out by 2015.
In the UK alone, losses could be up to 254,000 jobs and 7.8bn euros, it said.
According to the UK government, the creative industries in the UK employ around 2 million people.
Agnete Haaland, the president of the International Actors' Federation, which supports the research, said that education was key to tackling piracy.
"We should change the word piracy," she said.
"To me, piracy is something adventurous, it makes you think about Johnny Depp.
"But we're talking about a criminal act. We're talking about making it impossible to make a living from what you do."
She urged the European Parliament to implement rules to tackle online piracy.
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