Hillary Clinton's family charity has accepted contributions from donors accused of violating sanctions against Iran.
Her husband has also received a generous payment for a speech hosted by a company with financial interests in Iran.
The ties to Iranian business raise questions about Clinton's cautious support of a nuclear deal that would lift sanctions that prevent companies close to her from making money in Iran.
For example, a British company whose chairman is a member of the Clinton Global Initiative pleaded guilty to violating sanctions against Iran, the Daily Beast noted Friday.
Vahid Alaghband, who was born in Iran, founded Balli Group in 1991. That company gave between $10,000 and $25,000 to the Clinton Foundation, donor records show.
Alaghband has highlighted his personal involvement with the Clinton Global Initiative.
Balli Aviation, an arm of Balli Group, was faulted by the Justice Department in 2010 for exporting Boeing airplanes to Iran despite international sanctions against such transactions.
"Tightening sanctions against Iran have made it increasingly difficult for the trader to conduct business," an industry publication wrote of Alaghband's company in 2013.
In 2008, then-Secretary of State Condoleezza Rice circulated a diplomatic cable that warned about Balli's associations as it prepared to ship three airplanes to Iran that were undergoing maintenance in South Korea.
"The Balli Group is composed of expatriate Iranian owners who maintain ties to Iranian regime members," Rice said.
Other Clinton Foundation donors have seemingly flirted with violations of the bans on Iranian commerce without facing the same legal consequences.
Victor Pinchuk, the single largest donor to the Clinton Foundation, owns a manufacturer that shipped railroad parts, among other products, to Iran during the last two years of Clinton's time as secretary.
The company, Interpipe Group, shipped nearly $2 million of oil pipeline to Iran in May 2012, according to a Newsweek report.
Pinchuk and Interpipe denied allegations that they had violated U.S. economic sanctions.
But Interpipe's own website boasts of the company's experience working with railroads in Iran.
In 2013, an Interpipe financial report quoted by the Ukraine Business Daily said Pinchuk's firm touted "regions of the Middle East, Central Asia, including Syria, Iran, Libya and Algeria, and NAFTA countries (the United States, Canada and Mexico)" among its "most dynamic markets."
As secretary, Clinton wielded considerable authority over which foreign companies could face consequences for violating U.S.-imposed sanctions.
She was also involved in deciding which industries would fall under the expanding umbrella of sanctions against Iran in 2011 and 2012.
During that time, Bill Clinton was invited to deliver a speech in Hong Kong by Ericsson, a Swedish telecommunications company with business ties to Iran.
The former president reportedly netted $750,000 for the speech.
Sanctions imposed on telecommunications companies months after the event did not include Ericsson's work in Iran, Peter Schweizer noted in his book Clinton Cash.
A July 2013 report from the Congressional Research Service indicated Ericsson was still "active" in Iran and that the company was in talks "to help build a network for Irancell," a private cellular service in the country.
Another top Clinton Foundation donor has openly expressed interest in the profits that would follow the removal of sanctions against Iran.
United Oil Products, British subsidiary of well-connected Clinton Foundation donor Honeywell, was still involved in the Iranian oil market the same year the U.S. handed down stricter sanctions against companies working in the Iranian energy sector.
UOP was part of a consortium that was tapped to perform work at the Arak refinery, according to the Foundation for Defense of Democracy.
Arak is the location of one of Iran's largest and most controversial nuclear sites.
A top executive at Honeywell's UOP said the company has already begun outlining plans to delve back into the Iranian market once sanctions are lifted, predicting "massive investment in the upgrade of refineries" after the talks are completed, according to Gulf News.
In September 2009, Hillary Clinton questioned her aides about the possibility of helping Honeywell increase its sales by easing export controls that "interfere" with profits, according to emails released by the State Department last month.
She noted the CEO of Honeywell had personally approached her with the issue, but the exact favor he asked of Clinton was redacted by the State Department.