Among the revelations from the Panama Papers comes news of a business interaction between global banking giant HSBC and Rami Makhlouf, the Syrian business tycoon and the maternal cousin of Syrian President Bashar al-Assad.

A 'Wikileaked' American State Department cable from 2008 says: "Makhlouf has used government instruments to squeeze out legitimate businessmen, receive lucrative public contracts, establish cash cows and then milk them with impunity from oversight or competition." He became the subject of American sanctions that year. Nonetheless, Mossack Fonseca remained the registered agent of various companies in the British Virgin Islands linked to Makhlouf during the 'Arab Spring' of 2011, even though its own compliance officer warned: “I believe if an individual is found on a sanction list then this is a serious red flag and we should make every effort to disassociate ourselves from them.”

Meanwhile, the leaked documents show that HSBC provided Drex Technologies, one of Makhlouf's companies, with financial services. As late as 2010 the banking giant was assuring Mossack Fonseca that the company was “of good standing.”

The International Consortium of Investigative Journalists, which publicised the leaks, writes: "Makhlouf’s individual HSBC file linked him to at least 18 bank accounts connected to 14 client accounts. Six of them were numbered accounts. At their combined maximum in 2006/2007, these 14 accounts held over $27.5 million. He was beneficial owner of three of them: Polter Investments Inc; Lorie Limited, set up in 1999 and closed in 2004; and Drex Technologies SA, which was registered in Luxembourg and was sanctioned in 2012 by several countries including the United States and Canada and by the European Union."

HSBC also lobbied successfully to keep Makhlouf's aforementioned Swiss bank accounts open right up until the turmoil surrounding the Arab Spring forced Western governments to take a harder line than before. An email from Mossack Fonseca's office in Geneva in February 2011 states that HSBC's compliance departments in Geneva and in London were 'comfortable' with the relationship. This changed, however, in May 2011 when he ended up on an EU blacklist. Swiss regulators froze his family's accounts on 19th May.