Thirty five current and former leaders are featured in roughly 11.9 million documents leaked from financial services companies that include reports of luxury mansions on the French Riviera, Monte Carlo and California.
The so-called "Pandora Papers" were obtained by the International Consortium of Investigative Journalists (ICIJ) and released in stories by media partners including The Washington Post, the BBC and The Guardian.
Allegations range from corruption to money laundering and tax evasion.
Holding assets offshore or using shell companies is not illegal in most countries, but the revelations are embarrassing for leaders who have pushed austerity measures or campaigned against corruption.
While Russian leader Vladimir Putin is not named, he is linked via associates to secret assets in Monaco, including a waterfront home acquired by a Russian woman reported to have had a child with him.
"This is just a set of largely unsubstantiated claims," said Kremlin spokesman Dmitry Peskov.
"We didn't see anything on hidden wealth within Putin's inner circle."
Jordan rejected as "distorted" reports that King Abdullah II created a network of offshore companies and tax havens to amass a $100 million property empire stretching from California to London.
'Nothing To Hide'
Abdullah did not directly address the issue but denounced what he called a "campaign against Jordan".
"Attempts to embarrass Jordan have been going on for some time, and there are still those who want to sabotage it and sow suspicions," a royal court statement quoted him as saying to a group of tribal elders.
"We have nothing to hide".
The country's royal court said the properties were funded with the king's personal wealth and were used for official and private visits.
Ivory Coast Prime Minister Patrick Achi also denied wrongdoing after allegations that he became the owner of Bahamas-based company Allstar Consultancy Services Ltd through a trust that obscured his ownership.
Achi's office denounced the "malicious use seemingly being made of this information" that dates back to the late 1990s when he was an adviser to Ivory Coast's energy minister.
Achi "will not allow his name to be linked with illicit activities and thereby sullied", the statement added.
Kenyan President Uhuru Kenyatta said the papers would "enhance financial transparency", but sidestepped allegations that his family owned 11 offshore companies worth millions of dollars.
"The movement of illicit funds, proceeds of crime and corruption thrive in an environment of secrecy and darkness," said Kenyatta, the son of independent Kenya's first president.
Czech PM Hits Back
The ICIJ found links between almost 1,000 companies in offshore havens and 336 high-level politicians and public officials.
Among them were more than a dozen serving heads of state and government, country leaders, cabinet ministers, ambassadors and others.
More than two-thirds of the companies were set up in the British Virgin Islands.
Family and associates of Azerbaijani President Ilham Aliyev -- long accused of corruption in the central Asian nation -- are alleged to have been secretly involved in property deals in Britain worth hundreds of millions.
The documents also show how Czech Prime Minister Andrej Babis -- who faces an election later this week -- failed to declare an offshore investment company used to purchase a chateau worth $22 million in the south of France.
"I have never done anything illegal or wrong," Babis tweeted, calling the revelations a smear attempt aimed at influencing the election.
Nearly two million of the 11.9 million leaked documents came from a Panamanian law firm called Alcogal.
Alcogal has rejected accusations of shady dealings.
ICIJ's director Gerard Ryle said in a video accompanying the investigation that those best placed to halt such practices were the ones benefiting the most.
Transparency International's Maira Martini called for an end to the offshore industry, saying the investigation once more offered "clear evidence" of how it "promotes corruption and financial crime".
European Union chief Ursula von der Leyen said the bloc needed to do "more work" to combat tax evasion.
Among the other revelations from the ICIJ investigation:
-- Britain's former prime minister Tony Blair is shown to have legally avoided paying stamp duty on a London property by buying the offshore company that owned it.
-- Members of Pakistan Prime Minister Imran Khan's inner circle are said to secretly own companies and trusts holding millions of dollars. Khan vowed to "take appropriate action" if any wrongdoing is proved.
-- Congo President Denis Sassou Nguesso and Gabon's Ali Bongo were linked with companies in the British Virgin Islands in a report by Le Monde, one of the media partners in the investigation.
-- Colombian singer Shakira, the German supermodel Claudia Schiffer and the Indian cricket legend Sachin Tendulkar are also named, with representatives for all three telling the ICIJ the investments were legitimate.
The "Pandora Papers" are the latest in a series of mass leaks handled by the ICIJ, from LuxLeaks in 2014, to the 2016 Panama Papers.
They were followed by the Paradise Papers in 2017 and FinCen files in 2020.