A frustrated Hillary Clinton on Thursday told an activist that she was "so sick" of Bernie Sanders' campaign's lies about her accepting donations from the fossil fuel industry.

In the exchange, posted online by Greenpeace, Clinton is questioned by an activist on whether she would reject contributions from fossil fuel companies.

"I do not have — I have money from people who work for fossil fuel companies. I am so sick — I am so sick of the Sanders campaign lying about me," Clinton said, pointing her finger forcefully at the woman who asked the question."I’m sick of it."

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During the course of the race Sanders and his surrogates have slammed Clinton for taking contributions from the fossil-fuel industry.

During a March primary debate in Flint, Michigan Sanders said that instead of standing up to the "corrupt campaign finance system," a super PAC supporting Clinton was raising "huge amounts...a lot of money from Wall Street and the fossil-fuel industry."

Earlier this month, Vice News reported that fossil fuel interests have "pumped $3.25 million into" Priorities USA Action, a pro-Clinton super PAC.

Clinton's presidential campaign received roughly $307,000 in contributions from those employed in the oil and gas industries, according to the Center for Responsive Politics. Sanders, in comparison, received roughly $54,000.

Clinton has donors and bundlers from fossil fuel companies. Think she's parsing individuals versus corporate $ here. Not a great look. — Jennifer Epstein (@jeneps) March 31, 2016

The Sanders campaign issued a statement via campaign spokesman Michael Briggs, saying:

“The truth is that Secretary Clinton has relied heavily on funds from lobbyists working for the oil, gas and coal industry. According to an analysis by Greenpeace, Hillary Clinton's campaign and her super PAC have received more than $4.5 million from the fossil fuel industry. In fact, 57 oil, gas and coal industry lobbyists have directly contributed to Clinton’s campaign, with 43 of them contributing the maximum allowed for the primary. Eleven of those 53 lobbyists are working as bundlers and have raised over $1.1 million in bundled contributions between them.

Later Thursday, Clinton spokesperson Nick Merrill issued a statement saying that the Sanders campaign, "should stop the false attacks and do what they've claimed the campaign is about: debating the issues."

Clinton camp statement on the Greenpeace exchange,

via spokesman @nickmerrill pic.twitter.com/l4o0yAuaCY — Liz Kreutz (@ABCLiz) March 31, 2016

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