MADRID: A former HSBC employee fighting extradition to Switzerland for allegedly stealing and revealing confidential information about private Swiss accounts said Monday the material in his possession highlights "scandalous'' levels of tax evasion and money-laundering.

Herve Falciani faces charges of stealing information between 2006 and 2007 related to 24,000 customers with private accounts with the Swiss division of global banking group HSBC while he worked in the bank's information technology development unit.

France's former Finance Minister, Christine Lagarde, now head of the International Monetary Fund, passed the list on to the U.S. and several European Union countries, thereby exposing many of the bank's customers to prosecution for tax evasion.

Swiss authorities want Falciani, who has French and Italian citizenship, sent back to Switzerland to face charges of allegedly revealing secrets and breach of banking secrecy _ which could lead to a seven-year jail term.

However, Falciani told a Spanish court hearing the extradition request that he had informed Swiss authorities in 2008 about what he had discovered at HSBC Private Bank (Suisse) SA but they refused to let him make an anonymous complaint.

"I wanted it to be anonymous because I feared for my life,'' Falciani told Spain's National Court, speaking in French.

Spanish authorities have sided with Falciani, saying he has collaborated with governments around the world which are looking to crack down on tax evasion, including Spain where a recession and high unemployment have made it a touchy issue.

Falciani told the court in Madrid his intention was to raise the alarm about what was going on at the bank. He denied he sought to sell the information.

"Wikileaks and the international press would love to get their hands on this hard drive,'' Falciani's lawyer, Juan Garces, told the court.

Falciani claimed he did not have direct access to customer account information at the bank. Colleagues at HSBC, who he did not identify, passed him the evidence, he said.

The "huge number'' of documents suggested tax evasion and money-laundering via the accounts, according to Falciani, who described their content as "scandalous.''

HSBC PLC said offering private banking services for rich customers remained ``a core business'' of the group which has about 100,000 such clients.

Falciani fled Switzerland to France in 2008 and was held in custody in July last year after being arrested on a Swiss warrant while he was in the northeastern city of Barcelona.

In December 2012, the National Court released him after the Spanish authorities argued Falciani was cooperating with authorities in several European countries in investigations into tax evasion, money-laundering, corruption and terrorism financing.

Falciani was released on condition he handed over his passport, did not leave Spain and reported to a police station every three days. He was also ordered to establish a residence in Spain and to inform authorities if he moved house.

The court is expected to give its verdict in coming weeks.