Panama Papers | Internationally sanctioned entities among Mossack Fonseca clients

In several cases Mossack Fonseca continued to act as a proxy for sanctioned businesses even after they were blacklisted

The Panama legal firm at the heart of a massive data leak kept clients who were subject to international sanctions, documents show.

Mossack Fonseca worked with 33 individuals or companies who have been placed under sanctions by the US Treasury, including companies based in Iran, Zimbabwe and North Korea. One had links to North Korea's nuclear weapons programme.

The information comes from the leak of 11 million of the company's internal files.

Mossack Fonseca registers companies as offshore entities operated under its own name. This meant the identities of the real owners were hard to trace because they were kept out of public documents.

Some of the businesses were registered before international sanctions were imposed. But in several cases Mossack Fonseca continued to act as a proxy for them after they were blacklisted.

DCB Finance was established in 2006, with its owners and directors based in North Korea's capital Pyongyang. It was later put under sanctions by the US Treasury for raising funds for the North Korean regime and being linked to a bank helping to fund the regime's nuclear weapons programme.

Another case involves Rami Makhlouf, who is the cousin of Syria's President Bashar al-Assad and has reported wealth of $5bn.

In 2008 the US Treasury imposed sanctions on him because it deemed him to be a "regime insider" and someone who "manipulated the Syrian judicial system and used Syrian intelligence officials to intimidate his business rivals".

Mossack Fonseca cut all its links with Rami Makhlouf in September 2011, nine months after it was first recommended.

But the leaked documents reveal the firm also provided business services to another company that was registered on a US sanctions list in 2014.

The company is called Pangates International Corporation Limited. The US Treasury Department believes it supplied aviation fuel to the Syrian government to fly military aircraft during the current civil war. The files show Mossack Fonseca first incorporated the petroleum firm in 1999.