The law firm at the epicentre of the Panama papers leak shifted money for firms in North Korea, Iran and Zimbabwe

Mossack Fonseca - the law firm at the centre of one of the largest data dumps in history - worked with 33 individuals or companies that were under sanctions from the US Treasury, according to the BBC.

On Sunday evening, over 11 million documents held by the Panama-based law firm Mossack Fonseca was leaked to German newspaper Suddeutsche Zeitung.

In turn, the paper shared the information with the International Consortium of Investigative Journalists (ICIJ) - which is made up of 107 media organisations in 78 countries. The BBC was one of those organisations that has seen the documents, although it said it "doesn't know the identity of the source.

The year-long investigation revealed where 140 political figures - including 12 current of former heads of states - hide their cash.

The BBC said that its analysis of the documents show that some of the companies Mossack Fonseca worked for included those based in North Korea, Zimbabwe, and Iran.

The BBC said this is how they did it:

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.

You can read the full investigation, including that of the other sanctioned individuals and firms, by the BBC here.