On paper, the Clinton Foundation looks unimpeachable: a charitable organization dedicated to improving millions of lives through education and health.
However, it remains mired in suspicions about conflicts of interest involving the Democratic candidate for the White House.
Three months before the US presidential election, Hillary Clinton's opponents accuse her almost daily of having used her influence as secretary of state in 2009-2013 for the benefit of the foundation her husband and former president, Bill, founded in 2001.
"When will we see stories from CNN on Clinton Foundation corruption and Hillary's pay-for-play at State Department?" Clinton's Republican rival for the White House, Donald Trump, recently tweeted.
He had already called for the the woman he taunts as "Crooked Hillary" to repay millions of dollars of Saudi donations to the foundation.
In mid-July, more than 60 Republicans in Congress urged the FBI and the IRS to open an investigation into an organization they consider "lawless" and the subject of "significant issues of public corruption," according to their letter, obtained by AFP.
Clinton has consistently dismissed the accusations.
"There's absolutely no connection between anything that I did as a secretary of state and the Clinton foundation," she said on Fox News late last month.
- Generous donors -
Unsurprisingly, the attacks have focused on the financing of an organization whose resources have soared by almost 475 percent in a decade to exceed $337 million, according to its internal audits.
Its generous donor contributions -- $217 million in 2014 -- have prompted controversy, especially those from foreign governments: Saudi Arabia ($10 to $25 million), Kuwait (up to $10 million), Qatar and the United Arab Emirates (up to $5 million), according to the foundation's figures.
Multinational companies -- Coca-Cola, Barclays, General Electric among them -- have also supported projects of the foundation which boasts having facilitated access to HIV treatment for 11.5 million people.
Although the donations -- the dates of which are unclear -- involve no known illegal act, some argue they were granted in exchange for a sympathetic ear among the US authorities.
In an article published in 2015, the New York Times suggested that the State Department, headed by Clinton at the time, approved -- along with other departments of the US government -- the Russian nuclear power agency's acquisition of a major Canadian company, Uranium One, some of whose shareholders were major donors to the Clinton Foundation.
Clinton's supporters have dismissed the accusations as unfounded.
- Opacity -
But the case revealed an inconvenient fact: some donations were not made public, contrary to commitments Clinton made before taking up her post at the State Department in early 2009 and leaving the foundation at the same time.
A December 2008 memorandum obliged the foundation to reveal the name of new donors for approval by the State Department in order to avoid any potential conflicts of interest.
However, that rule was ignored for a contribution of $500,000 by Algeria in 2010, The Washington Post reported in February 2015.
The same year, the foundation admitted "mistakes" in its tax returns, prompting another volley of sometimes surreal suspicions.
On Monday, Trump's campaign team accused the Clinton Foundation of having accepted a donation from a business with links to the Islamic State group -- the French group Lafarge, which was active in territory controlled by the jihadists, Le Monde newspaper reported.
"People who don't like the Clinton will make up a reason to attack the Clinton Foundation," said Daniel Borochoff of Charity Watch, an independent group that observes humanitarian organizations, adding that donations from foreign countries are common.
If Clinton is elected president in November, however, the foundation will have to make changes to head off the suspicions, her husband said in June. "You have to be careful to avoid actual or potential conflicts of interest," he said.
The Clinton Foundation did not respond to numerous requests for comment from AFP.