The secret dealings of hundreds of world leaders, politicians and billionaires have been exposed in one of the biggest investigations of leaked offshore documents in history.

The leak of almost 12 million documents reveals hidden wealth, tax avoidance and, in some cases, money laundering by some of the world's rich and powerful.

Paul Tang, chair of the European Parliament’s tax subcommittee, told BBC World News that he thought a lot could be done to tackle these issues including looking into shell companies - those companies which exist in name only without staff or offices.

He was also optimistic about how the public will pressure politicians for reforms.

More than 600 journalists in 117 countries trawled through files from 14 sources for months. The data was obtained by the International Consortium of Investigative Journalists (ICIJ) in Washington DC.