He warned that the leak of documents exposing offshore tax havens shows “rapid movement” toward a group of billionaires controlling the global economy.

Bernie Sanders has warned that the world is rapidly becoming an “international oligarchy” controlled by a tiny number of billionaires, highlighted by the revelations in the Paradise Papers.

In a statement to the Guardian in the wake of the massive leak of documents exposing the secrets of offshore investors, Sanders said that the enrichment of wealthy individuals and companies in tax havens was “the major issue of our time”.

He said the Paradise Papers opened the door on a “major problem not just for the US but for governments throughout the world”.

“The major issue of our time is the rapid movement toward international oligarchy in which a handful of billionaires own and control a significant part of the global economy. The Paradise Papers shows how these billionaires and multinational corporations get richer by hiding their wealth and profits and avoid paying their fair share of taxes,” the US senator from Vermont said.

Sanders, who came in a close second to Hillary Clinton in the race for the Democratic presidential nomination last year, pointed the finger of blame for the flourishing of offshore holdings on both Congress and the Trump administration. He told the Guardian that Republicans in Congress were responsible for providing “even more tax breaks to profitable corporations like Apple and Nike”.

The same tax breaks, he said, were being seized upon by super-wealthy members of Trump’s cabinet “who avoid billions in US taxes by shifting American jobs and profits to offshore tax havens. We need to close these loopholes and demand a fair and progressive tax system.”

Sanders’ intervention in the debate sparked by the Paradise Papers marks the most prominent political response to the leak in their opening 24 hours. The investigation stems from the leak of some 13m files obtained by Süddeutsche Zeitung in Germany and shared with almost 100 news organisations around the world including the Guardian by the International Consortium of Investigative Journalists.

One of the most pointed disclosures in the Paradise Papers was that Wilbur Ross, Trump’s commerce secretary, has continued to do business with the son-in-law of the Russian president, Vladimir Putin, as well as a member of Putin’s inner circle who is under US sanctions. Ross, himself a billionaire, has retained since joining the Trump administration his investment in a shipping company, Navigator, that has a partnership with the Russian gas giant Sibur.