Icelandic fishing giant Samherji is renewing its attack on the integrity of a whistleblower who sparked an investigation into the alleged "cash for quotas" scandal inside its Namibian fishing operations.

Samherji executives were angered by an interview conducted by IntraFish sister publication Dagens Naeringsliv (DN) with its former CEO of Samherji's operations in Namibia Johannes Stefansson earlier this month.

The cash-for-quotas scandal came to light after Stefansson made serious bribery allegations against the company.

Samherji complained Stefansson has declined to participate in a costly and time-consuming investigation by international law firm Wikborg Rein appointed by the company with the aim of getting to the bottom of the matter.

"Yet again, in DN recently, a media outlet gives a microphone to Johannes Stefansson without challenging his narrative in any notable manner," Samherji Co-CEO Bjorgolfur Johannsson said.

"I should point out the obvious and critical fact that Johannes Stefansson does not make allegations about what he observed, but rather about alleged wrongdoing he himself committed as an autonomous top manager for one of Samherji's subsidiaries, very far from Iceland."

Stefansson, who became a whistleblower working with Nambian anti-corruption authorities, admitted implementing bribe payments on the authorization of former CEO Thorsteinn Mar Baldvinsson who stepped aside to allow the internal probe to be conducted.

At the time, WikiLeaks published more than over 30,000 documents it said it obtained from a whistle-blower within Samherji.

Stefansson says he has faced threats in recent years from "sharks" involved in Namibia's cash-for-quotas scandal, leaving him constantly on guard.

Baldvinsson has since returned to lead Samherji.

Samherji is standing firmly by its denial that the company's management ever intended for any subsidiary to engage in wrongful activity, including bribery or money laundering.

Its denial follows the recent delivery to the company of an investigative report by Wikborg Rein, findings of which have not yet been made public.

In an op-ed released to the media, Johannsson pushed back on Stefansson's assertions in the DN story that "this is the way they do it," and that he "must be loyal to the boss."

"Samherji as a group has operated in a number of countries for almost 40 years," Johansson said. "This is the first time ever we are subject to these kinds of allegations."

Johansson further noted that Stefansson acted not on the company's behest, but operated autonomously for the subsidiary.

"As part of his interview with [DN], Johannes Stefansson is asked if he ever considered notifying anyone internally in Samherji," Johansson wrote.

"This is a very good question, and Johannes is evasive in his reply. The fact of the matter is that Johannes never notified [anyone] of alleged wrongdoing internally in Samherji, neither to management, the board of directors, auditors or anyone else who could have actually addressed the alleged matters."

Notification of potential wrongdoing within a company is the first rule for whistleblowers, Johansson said.

"Only if such attempts are unsuccessful, media is considered an appropriate channel," he added.

"Such established best practice stands in stark contrast to Johannes Stefansson's actions. There is very little in his conduct that indicates a genuine interest in addressing the alleged issues he so eagerly speaks to journalists about in a targeted and constructive manner. Instead, it seems that there has been a commitment to take part in a targeted campaign against Samherji."

Johansson further criticized Icelandic journalists for their handling of Stefansson's allegations.

"There is no doubt that Samherji has failed to protect subsidiaries against the wrongdoing of individuals. We deeply regret that," he added, highlighting the upcoming publication of the Wikborg Rein report.