Sen. David Vitter (R., La.) wants to know whether Hillary Clinton concealed communications with a Nigerian donor to the Clinton Foundation during an internal State Department debate over designating Boko Haram a terrorist group.

Vitter sent a letter last week to Secretary of State John Kerry requesting all of Clinton’s records relating to Boko Haram and her reluctance to label it as a Foreign Terrorist Organization (FTO).

The senator also asked for all of Secretary Clinton’s communications with Gilbert Chagoury, a Nigerian construction magnate who has donated millions to the Clinton Foundation in addition to contributing thousands to an outside group that helped re-elect President Bill Clinton in 1996.

Vitter said in an interview with the Washington Free Beacon that he wants to uncover whether Chagoury’s relationship with the former secretary of state influenced her policy toward Nigeria and its radical Islamic insurgency.

As founder of the Chagoury Group, one of Nigeria’s largest construction conglomerates, Chagoury would have a financial interest in the impact on Nigeria that would have followed a FTO designation for Boko Haram, Vitter said.

"He’s not Boko Haram, but he has a clear interest in terms of his commercial developments of not getting this designation, which would put the brakes on a lot of possible development that he wants in Nigeria," he told the Free Beacon.

"The question I’ve raised is: Is there a similar conflict of interest there? And did that sort of issue have anything to do with Hillary Clinton’s State Department dragging its feet?"

Mark Corallo, a spokesman for Chagoury and Republican consultant who formerly worked at the Justice Department and on Capitol Hill, said in an email statement that accusations of an improper relationship between Chagoury and Clinton are "ludicrous and laughable."

"Chagoury has had no contact with Hillary Clinton for years—predating her time as a U.S. senator," he said. "So even if Senator Vitter somehow retrieves Hillary’s emails (and I hope he does), he’ll find no emails or correspondence of any kind from Ambassador Chagoury with Secretary Clinton or the Department of State."

"Furthermore, while he has had a well-publicized friendship with former President Clinton and has donated to the Clinton Foundation, I would point out that he has also donated to the George W. Bush presidential library. Why? Because both President Bush and President Clinton showed a real interest in Africa and Ambassador Chagoury truly appreciated both men and their efforts."

A spokesman for Clinton did not respond to a request for comment. A spokeswoman for the State Department also did not respond to a query about whether Kerry had received Vitter’s letter, and how long it would take to provide the communications he requested.

Both Nigerian officials and outside observers who were opposed to the FTO designation for Boko Haram argued that such a move would have a negative economic impact on the country. Chagoury employs tens of thousands of workers in West Africa and has spearheaded some of Nigeria’s most ambitious development projects.

A group of more than 20 academics wrote Clinton a letter in 2012 urging her against the FTO designation, citing its effects on humanitarian and economic aid.

"If economic development is to play a role in alleviating tensions in northern Nigeria, we should not hamper access by USAID or private NGOs in providing aid and assistance in the region," they wrote.

The criticism of the FTO designation came as Johnnie Carson, former assistant secretary of state for African affairs under Clinton and an opponent of the measure, stressed the importance of private investment in Nigeria. The country is the second-largest destination in Africa for U.S. private investment.

The militant group was eventually declared as a FTO in November 2013 after Kerry became secretary of state.

Chagoury donated between $1,000,001 and $5,000,000 to the Clinton Foundation and pledged $1 billion to the Clinton Global Initiative in 2009 through the Chagoury Group. His relationship with the Clintons stretches back to the 1990s, when he contributed nearly half a million dollars to a voter registration group that helped re-elect President Bill Clinton in 1996.

At the time, human rights activists pressured Clinton to sanction Nigeria’s Sani Abacha regime for detaining and executing political dissidents. Chagoury, an Abacha associate, was reportedly invited to a White House dinner for Democratic supporters in 1997 and spoke with Clinton administration officials during that period about U.S. policy toward Nigeria. Clinton opted against sanctioning Nigeria’s profitable oil industry, instead pursuing "constructive dialogue" with the Abacha regime. Abacha died in 1998.

Several members of Chagoury’s family also donated thousands of dollars to Hillary Clinton’s failed presidential bid in 2008, according to the Wall Street Journal.

According to a 2010 investigation by PBS Frontline, Chagoury was one of the associates of Abacha’s who received government payments in overseas bank accounts.

He was convicted in 2000 in Switzerland for laundering money from Nigeria, but agreed to a plea deal and repaid $66 million to the Nigerian government. The conviction was later dropped. He also returned money in Swiss bank accounts to Nigeria in 1999 to receive immunity from prosecution in a looted assets case.

Corallo said the charges against Chagoury "were vacated and expunged from the record."

Chagoury was also linked to a scheme in which Kellogg, Brown, and Root (KBR), then a subsidiary of the Halliburton Corporation, paid $180 million in bribes to the Abacha regime for business contracts in the 1990s. KBR eventually agreed to pay $579 million in fines in 2009, the largest ever payment for a company accused of bribing foreign officials.

Chagoury was not charged with any wrongdoing during a Justice Department investigation of the exchange.

"You are never going to stop corruption," Chagoury told PBS.

Chagoury helped plan lucrative speeches for Bill Clinton and attended the former president’s 60th birthday party in 2006 in New York, as well as the wedding celebration in France of top Clinton aide Douglas Band, according to the Wall Street Journal.

Chagoury’s latest project, a land reclamation effort known as Eko Atlantic that will provide residences and amenities to 250,000 wealthy Nigerians outside of Lagos, has been criticized by some for not aiding Africa’s poor. Bill Clinton attended the groundbreaking ceremony for the project in February 2013.

Sen. Vitter has long suggested that State Department officials are downplaying the threat posed by Boko Haram.

He wrote a letter to Kerry last year about apparent discrepancies between statistics provided to the State Department and the actual language included in the department’s annual reports on global terrorism.

For example, the National Counterterrorism Center’s (NCTC) statistical annex for the 2011 State Department report said that a double-digit percentage increase in attacks in Africa was "attributable in large part to the more aggressive attack tempo of the Nigeria-based terrorist group Boko Haram, which conducted 136 attacks in 2011­—up from 31 in 2010."

However, the actual Country Reports on Terrorism for 2011 only called Boko Haram a "Nigerian extremist group" that "claimed responsibility for some of these attacks."