The committee also wants to know if new legislation could disrupt the business model of banks and lawyers that help rich individuals and companies to minimise their tax bill through different offshore schemes.

The Panama leaks showed that a Panamanian law firm, Mossack Fonseca, set up shell firms for hoards of European clients.

Highlighting the coamplexity of the problem, Jan Strozyk from German radio station NDR, told the MEPs: “Mossack Fonseca doesn’t actually work with customers directly”.

”There is a whole industry of middlemen and intermediaries: bankers, lawyers, accountants, consultants, and one-stop-shops”.

Six of Germany’s seven largest banks, including some state-owned banks, also offered Fonseca-type services, he added.

Another NDR reporter, Julia Stein, said she set up her own shell company with a few mouse clicks and no questions asked.

”It was like shopping on Amazon,” she said. ”You Google, and find lots of advertisements on how easy it is to open a shell company”.

Kristof Clerix, a Belgian journalist, said shell firms “can be used for legal, illegal, or even criminal activities”.

He said that, for him, it was OK to use offshore entities to conceal wealth from business partners or spouses, but not in order to trick tax authorities.

Oliver Zihlmann, from the Swiss newspaper Sonntagszeitung, noted: “We have found cases of child abusers, arms smugglers, and terrorists using these [hidden] funds”.

He also highlighted the political risks of shadow structures.

He said that Panama Papers had exposed the fact that Russian leader Vladimir Putin’s “closest entourage” had channelled hundreds of millions of euros through the EU while avoiding controls.

He singled out Cyprus for criticism, saying that while it had a register of corporate ownership on paper, in reality ”nobody is filling it out.”

Journalists, such as Finland’s Minna Knus, also called for a new EU law to protect whistleblowers.

Kroes affair

The mood in the committee’s first meeting was upbeat on Tuesday.

MEPs were concerned, however, the legal service of the EU Council, where member sates meet, had issued an opinion earlier this summer saying the MEPs cannot have full access to information.

The Pana chairman, German centre-right MEP Werner Langen, vowed to fight for the European parliament's right to have the same kind of powers as inquests in national assemblies.

Further clouds on the horizon could appear as the parliament tries to summon guests to its next hearings.

Langen said former EU commissioner Neelie Kroes, recently exposed for having failed to declare her role in an offshore firm while in office, should face the committee’s questions.

When asked whether the current climate change commissioner, Miguel Arias Canete, who failed to declare his wife’s Mossack Fonseca shell firm, should also face questions, the MEP said ”active politicians” would be called up.

He also mentioned Malta’s minister of energy, Konrad Mizzi, another Mossack Fonseca client, as an example.

The decision on who to invite will be taken on 13 October, but Canete’s centre-right EPP political family and the European Commission might try to shield him from any cross-examination.