Compiled by Jessica Durando

USA TODAY

Corrections & Clarifications: A previous version of this story misstated the number of world leaders linked to offshore holdings. The documents identify 12 current or former leaders and 60 family members or associates.

The massive, anonymous leak Sunday of more than 11 million documents belonging to a law firm in Panama — Mossack Fonseca — that detail how powerful people hid their wealth reveals suspected cases of money laundering, sanctions evasion and tax avoidance.

Here's what you need to know:

Denials from world leaders are rolling out.

Iceland's prime minister, Sigmundur David Gunnlaugsson, faces a no-confidence vote later Monday for allegations in the documents that he deliberately hid holdings in Icelandic banks. Gunnlaugsson denies any wrongdoing and said on Icelandic television he would not resign.

News reports allege that Gunnlaughsson and his wife established a company in the British Virgin Islands with the help of Mossack Fonseca.

Panama Papers: Naming names of powerful officials

In Russia, the government said President Vladimir Putin has not committed a crime.

While Putin's name does not appear on any of the records published, the paper trail does show that many of his associates and close friends — including musician Sergei Roldugin, godfather to his daughter Maria and the man who introduced him to his wife, Lyudmilla — made millions from deals that would have been hard to make without Putin's knowledge.

Dmitry Peskov, Putin's spokesman, told Russian news agency Interfax that it was "obvious" the aim of the release of the documents was to undermine the president ahead of parliamentary elections expected in September.

Prime Minister of Pakistan denied any wrongdoing after his daughter and son were linked to offshore companies, Reuters reported.

Lawmakers called for an investigation into information that Ukrainian President Petro Poroshenko had used an offshore firm to avoid tax. But Poroshenko defended his commitment to transparency.

"I believe I might be the first top official in Ukraine who treats declaring of assets, paying taxes, conflict of interest issues seriously," Poroshenko tweeted.

Public responses to allegations still scarce.

The Panama Papers show how 140 politicians from more than 50 countries — including 12 current or former world leaders — have links to Mossack Fonesca. The papers cover a period from the 1970s to December 2015.

Most of the people at the center of the allegations have not publicly responded to the vast trove of documents and data initially shared with German newspaper Suddeutsche Zeitung.

Syrian President Bashar Assad is linked to the Panama Papers through two cousins, Rami and Hafez Makhlouf.

The Australian Taxation Office said in a statement Monday it was investigating more than 800 wealthy Australians for possible tax evasion linked to their dealings with Mossack Fonseca.

Panama Papers: Who did what

Panama Papers explainer: What you should know

Mossack Fonseca has denied any accusations of illegal activity.

Mossack Fonseca — a law firm based in Panama with more than 40 offices worldwide — specializes in commercial law, trust services, investor advisory and international structures.

It operates in tax haven countries such as Switzerland and the British Virgin Islands.

The Washington-based International Consortium of Investigative Journalists said the documents involve 214,488 companies and 14,153 clients of Mossack Fonseca.

Mossack Fonseca denied all accusations of illegal activity. The firm said it is a responsible member of the global financial community.

The cache is much bigger than WikiLeaks.

The trove of documents is bigger than the one leaked in 2013 by former CIA employee Edward Snowden — who tweeted on Sunday that the "Biggest leak in the history of data journalism just went live, and it's about corruption."

Sueddeutsche Zeitung, a Munich-based newspaper, said Sunday that the 11.5 million-document cache, which includes 4.8 million emails and nearly 2.5 million documents, is several times larger than a previous cache of offshore data published by WikiLeaks in 2013.

Reporting by Gregg Toppo, Kim Hjelmgaard, Susan Miller