A new report has revealed that global banking giant HSBC helped a motley crew of weapons dealers, tax evaders, tin-pot dictators and celebrities, to conceal at least USD 100 billion using the bank's private Swiss arm.

The International Consortium of Investigative Journalists (ICIJ) has analyzed the documents and revealed how the secretive Swiss banking system was used by HSBC to conceal the identities of accounts holders. The report added that the bank also helped many depositors avoid paying taxes.

The ICIJ said that its findings are based on data turned over to French authorities by former HSBC employee Herve Falciani in 2008. Le Monde newspaper later obtained the files and shared it with other media outlets.

ICIJ said the leaked documents show that HSBC "repeatedly reassured clients that it would not disclose details of accounts to national authorities" and even "discussed with clients a range of measures that would ultimately allow clients to avoid paying taxes in their home countries."

HSBC has said in a statement provided to ICIJ that its Swiss private bank has undergone a "radical transformation in recent years," including reforms that will make it more difficult for clients to evade taxes or launder money.

"We acknowledge that the compliance culture and standards of due diligence in HSBC's Swiss private bank, as well as the industry in general, were significantly lower than they are today," the statement said.

According to ICIJ, HSBC "served those close" to regimes including that of former Egyptian President Hosni Mubarak, former Tunisian President Ben Ali and current Syrian ruler Bashar al-Assad.

Other clients included former and current politicians from Britain, Russia, Ukraine, Georgia, Romania, India, the Democratic Republic of the Congo, Rwanda and Senegal, among others.