Rudolf Elmer is the latest in a line of high-profile bank whistleblowers

Fellow whistleblowers are vocal in their support for Rudolf Elmer as he hands over a disc with bank details of 2,000 well-known people to WikiLeaks founder Julian Assange.

Rudolf Elmer, a former employee of the Swiss Julius Baer bank, is not the first person to blow the whistle at individuals and institutions who use banking secrecy to facilitate money laundering and tax evasion. Nor is he likely to be the last.

As economies across the world slash public spending in the wake of the financial meltdown, there is a growing movement to promote transparency in international finance. How, the movement asks, is it right for a government to argue for a progressive system of domestic taxation while tolerating tax evasion and avoidance by some of its wealthiest citizens?

In the UK, the Tax Justice Network argues that "by draining reputable jurisdictions of the tax dollars of their wealthiest citizens and corporations, and by fostering massive capital flight out of developing countries, they (tax havens) have made it so much harder for victims of the crisis to pay to clean up the mess."

When whistleblower Rudolf Elmer handed over two discs to WikiLeaks founder Julian Assange at a Frontline Club press conference on 17 January 2011, he described his own predicament more graphically. He told journalists how the problems of offshore banking had at first seemed to him like a mouse's tail. But then, he continued, "I started to pull on it a bit and it got bigger… It became a dragon, a fire-breathing dragon with several heads."

Elmer was fired in 2002 from his job as chief operating officer for a Cayman Islands subsidiary of the Julius Baer Group, a Swiss banking firm (total client assets in 2009: £160.4bn), for allegedly stealing documents. In 2008 WikiLeaks was temporarily closed down when it published a batch of documents relating to Julius Baer's offshore activities. The discs Elmer passed to Assange today are said to contain details of prominent companies and individuals covering the period from 1999 to 2009.

Alongside Elmer at the Frontline Club were other supporters of banking transparency. They included the Tax Justice Network's Jon Christensen, who suggested the secretive world of offshore tax management could be summed up in the words "Those who know don't talk and those who talk don't know", and Elmer's lawyer, Jack Blum, an American specialising in offshore tax abuse.

Blum attacked international arrangements for tax governance as "a system to prevent government authorities from sorting it out". He has previously condemned the fact that Elmer has been forced to appear in court in Switzerland for violating Swiss banking secrecy law - in the Cayman Islands, which fall outside Swiss jurisdiction.

Also attending the press conference was Martin Woods, a friend of Rudolf Elmer who describes himself as a member the informal support network that exists between whistleblowers. As compliance officer for the US Wachovia bank (acquired by Walls Fargo in 2008), Woods drew his employers' attention to what appeared to be the laundering of drug money from Mexico, and was fired for his troubles.

In 2009 Martin Woods testified before a grand jury in the United States, and the bank eventually agreed to pay a $160m penalty to settle drug laundering charges.

Woods now runs Hermes Forensic Solutions, a company which investigates financial crime. He and Elmer first met at the 2010 Offshore Alert Conference, where both were speakers. Alluding to the fact that Elmer has already spent a month in jail in 2005 in connection with his whistleblowing activities, Woods told Channel 4 News: "Rudy's had it harder than most whistleblowers. He's had a very difficult time. But he's a strong individual and he's still going."

Woods cites other names in the whistleblowers' pantheon. They include Charles Rawl, who drew attention to the allegedly unethical business practices of financier and sports sponsor Allen Stanford; Harry Markopolos, acclaimed for helping to bring Ponzi schemester Bernard Madoff to book; and Paul Moore, former head of risk at HBOS, who warned his bosses in 2003 and 2004 that HBOS was expanding its loan book to fast.

The contents of the discs now in the possession of WikiLeaks will be vetted before they appear online, a process that could take as little as two weeks. US investigative journalist Lucy Komisar believes the brouhahah surrounding the Frontline Club press conference "means people will now pay more attention to his documents because they will be released by WikiLeaks".

But by the time they are published, Swiss authorities will have subjected Rudolf Elmer and his family (he has a wife and two children) to his next challenge as he returns to his native Switzerland later this week to face trial for stealing information from Julius Baer.