Environmentalist filmmaker Josh Fox grew frustrated during a recent public radio interview when asked about apparent falsehoods in his Oscar-nominated 2010 documentary Gasland.

Fox asked an interviewer with Aspen public radio station KAJX to go "off the record" so he could explain why he represented a gas extraction lease created by a group of Pennsylvania landowners as a $100,000 offer from a gas company to extract natural gas from his land.

The document presented in Gasland was a draft of a lease that Northern Wayne Property Owners Alliance (NWPOA), a Pennsylvania landowners group, offered to gas companies exploring potential shale drilling operations in the area hoping to secure favorable terms for landowners, according to NWPOA members.

It was not, as Fox claimed in the film, an offer from one of those companies. The group also says Fox was never a member, as he told KAJX on Monday.

Fox used the document in his film to establish his personal stake in the fight over hydraulic fracturing, an innovative oil and gas extraction technique that he vilified in Gasland and a recently released sequel.

"One day I got a letter in the mail. It was from a natural gas company," Fox said in the first Gasland. "They told me that my land was on top of a formation called the Marcellus Shale. I could lease my land to this company, and I could receive a signing bonus of $4,750 an acre. Having 19.5 acres, that was nearly $100,000."

However, the lease shown in the film is actually a draft created by NWPOA, a group that describes itself as "an advocate for local landowners with oil and gas producers."

Two typos on the draft lease shown in Gasland revealed that it was created not by any gas company, but by the NWPOA.

The draft lease was presented to gas companies looking to extract gas in the area, but the companies turned it down, and a revised version without the typos was later drafted.

The 2012 documentary FrackNation first revealed that the contract Fox presented was neither a firm offer to lease his land, nor written by any gas company looking to do so. The documentary’s creators released a video on Wednesday highlighting Fox’s interview with KAJX.

When asked about that discrepancy by KAJX reporter Elise Thatcher, Fox said that he was a NWPOA member, but "dropped out at the stage where you had to sign" a lease.

NWPOA says that is flatly untrue. "In fact, Josh Fox was never a member of the NWPOA," it wrote on its website on Tuesday.

"I’m surprised that you were partaking in those conversations, because I didn’t understand that," Thatcher said during the interview.

Fox appeared to be frustrated, and asked Thatcher, "can we just jump off the record for a second here?"

During the interview, Fox decried FrackNation as a "willfully deceitful project." But his critics say misrepresentations about the NWPOA and its draft lease underscore Fox’s own disregard for the facts.

Phelim McAleer, the Irish journalist who, with his wife Ann McIlhenny, created FrackNation, said Fox’s claim on KAJX that he was NWPOA member is "a major change in the story."

"But the NWPOA say he was never a member of their group and was not even on their email list," McAleer wrote in an email. "His changed story was a lie. He has now told two lies about the origins of Gasland."

Tom Shepstone, an industry consultant and Pennsylvania business owner, said the lease’s origin "is fundamental to the entire theme of the movie and its counter-cultural hero of sorts. Yet, it’s a total fabrication."

"The truth is irrelevant for [Fox’s] purposes, only material to be cut from or pasted into the script when convenient," Shepstone said.