The National Security Agency (NSA) accidentally obtained the communications of top officials of Venezuela's state-owned oil company within the massive cache produced by its bulk collection of data, an internal memo published by whistleblower Edward Snowden suggests.

The former NSA contractor forwarded the document to the Intercept, a website run by Snowden associates Glenn Greenwald and Laura Poitras, which commented that the agency's accidental discovery of such valuable information discredits its mass surveillance efforts.

The memo was written by an NSA analyst who apparently stumbled upon the Petróleos de Venezuela (PDVSA) secrets, including more than 10,000 employee information forms containing email addresses, phone numbers, and other identifying details. The information could be used to retrieve communications stored in the federal agency's databases, as well as for future targeting.

"By sheer luck, (and a ton of hard work) I discovered an important new access to an existing target and am working with TAO to leverage a new mission capability," the unidentified analyst wrote.

The NSA employee, who managed to obtain 900 username and password combinations for PDVSA accounts, turned the access details over to Tailored Access Operations, the agency's top hacking team, to penetrate the state-owned company's network and infect its computers with malware, the Intercept claimed.

The website also suggested that the NSA's findings may have led to a recent U.S. investigation of PDVSA, which, according to Bloomberg, has jeopardized approximately $8 billion in crude refineries, storage terminals and pipeline networks.

The assets belong to three U.S. oil refineries owned by the oil company's Citgo subsidiary and include a 425,000-barrel-a-day refinery in Lake Charles, Louisiana, which features shipping docks and storage terminals, the business publication detailed.

Embattled Venezuelan President Nicolás Maduro, meanwhile, chided U.S. intelligence services for surveying Energy Minister Rafael Ramírez, who also served as PDVSA's president, United Press International noted.

According to UPI, Maduro announced his government would "initiate a comprehensive review of the relationship with the U.S. government because Venezuela is respected."