HSBC's Swiss private bank reportedly helped hide millions of dollars for drug traffickers, arms dealers, celebrities and a king as it helped wealthy clients around the world dodge taxes, according to a report based on leaked documents that lifts the veil on banking secrecy laws.

The report from the International Consortium of Investigative Journalists (ICIJ) and several news organizations comes as governments seek to crack down on tax evasion to bolster treasuries depleted by the financial crisis and stanch criticism that the rich aren't paying their fair share.

Academics estimate that $7.6 trillion is held in overseas tax havens, depriving governments of $200 billion a year in tax revenue, according to the ICIJ report.

The leaked documents cover the period up to 2007 and relate to accounts worth $100 billion held by more than 100,000 people and legal entities from 200 countries.

Some details of such operations were previously disclosed when the United States fined HSBC in 2012 for allowing criminals to use its branches for money laundering. The names of 2,000 Greeks with HSBC accounts were made public in 2010 and dubbed the Lagarde List, after former French finance minister Christine Lagarde. France passed the names to Greece to help it crack down on tax evasion.

Monday's report discloses a more detailed cache of data and information. French newspaper Le Monde — together with Moroccan investigative journalist Ahmed Benchemsi’s news site Free Arabs — found that Morocco’s King Mohammed VI was among the customers, with a clandestine bank account that held more than $9 million from mid-2006 to 2007. With few exceptions, it is illegal for Moroccans in Morocco to own bank accounts abroad.

In Britain, where HSBC is based, the report sparked criticism that tax authorities hadn't done more to penalize people who have illegally evaded taxes. The tax agency received $236 million from some of the 3,600 Britons identified as using the Geneva branch of HSBC, but only one has been prosecuted.

France, by contrast, launched 103 actions. France's Prime Minister Manuel Valls told Europe 1 radio on Monday that France is "very determined" to fight tax evasion and will continue to take action at home and in Europe.

In Britain, lawmakers reacted with outrage.

"You are left wondering, as you see the enormity of what has been going on, what it actually takes to bring a tax cheat to court," Margaret Hodge, chair of Parliament's Public Accounts Committee, told the BBC.

She also said that former HSBC chairman Stephen Green, who became the government's trade minister after he left the bank in 2010, must face serious questions about whether he was "asleep at the wheel, or he did know and he was therefore involved in dodgy tax practices."

HSBC stressed that the documents were from eight years ago and said that it has since implemented numerous initiatives designed to prevent its banking services from being used to evade taxes or launder money.

Franco Morra, CEO of HSBC's Swiss subsidiary, said that the new management had overhauled the business and shut down accounts from clients who "did not meet our high standards."

"These disclosures about historical business practices are a reminder that the old business model of Swiss private banking is no longer acceptable," he said in a statement.

The HSBC files were analyzed by Le Monde, The Guardian, the BBC and the Washington-based ICIJ.

Al Jazeera and wire services