Penguin has undertaken a “thorough” review of one of its books, Spanish colonel Pedro Baños’s How They Rule the World, after allegations of antisemitism were made against its author. The publisher concluded that while Baños’s views are “robust”, they are not antisemitic.

How They Rule the World, which promises to reveal “the 22 secret strategies of global power”, was published by Penguin Random House imprint Ebury Press in April. Author Jeremy Duns began drawing attention to the book after he spotted links between the title and the cover, which bears an image of octopus tentacles. The octopus has long been associated with antisemitism; Hitler refers in Mein Kampf to the octopus of the supposed Jewish conspiracy for world conquest, and it was a frequently used symbol in Nazi-era propaganda.

Comparing the Spanish language edition of How They Rule the World with the English text, Duns found a section about the Rothschild family, a banking dynasty subject to many antisemitic conspiracy theories, which does not appear in the English translation. The Spanish edition contains three references to the Rothschilds, none of which appear in the English, including a section that compares their wealth with other rich families, and concludes: “It is clear that [the Rothschilds’] economic power is gigantic. As is their ability to influence in all senses, an aspect that, when considering their traditional distance from the media spotlight, has led to multiple speculations about their capacity to intervene in key global decisions.”

Baños is described by Ebury Press as “one of Europe’s top specialists in geopolitics, terrorism and intelligence”. A colonel in the Spanish army, he was previously the chief of counter-intelligence and security for the European Army Corps. In interviews with Spanish media, Baños has called the Rothschilds dominant and likened them to the Illuminati. On Spanish TV, he also once accused Israel of being behind the assassination of John F Kennedy.

Duns accused Penguin of having knowingly published “a Spanish antisemitic conspiracy theorist … because to cover it up they’ve removed passages about the Rothschilds. I think you’ll agree this is a pretty serious problem we’re facing. As usual, it’s about fact-checking, research, due diligence, and not doing them.”

Penguin said it was aware of the “serious concerns” raised about How They Rule the World, telling the Guardian that they had prompted it to take a close look at both the book and the author.

“As a publisher who takes our responsibilities to our readers and our authors extremely seriously, we always undertake careful due diligence before committing any book to publication, and this book was no exception. However, given the serious nature of these concerns, we have undertaken a thorough review into the UK publication,” said the publisher in a statement.

“Our conclusion was that whilst the author clearly expresses robust opinions about geostrategies and geopolitics, focusing on the historical, psychological and social reasons for the alleged global domination of many different groups, he does not in our opinion express views in this publication, including in the parts omitted, that are antisemitic. Nor are there any legal concerns with this book or any known reputational issues with the author.”

In reference to the cover image, Penguin said that it had selected the tentacles “to reflect the octopus as a symbol of domination by an imperialist power … This symbolism has been widely used in political imagery from the 19th Century onward by many cultures about their most feared geopolitical rival, which is very pertinent to the subject of the book.”

Baños was not available for comment, but tweeted last week: “Classic disqualification to discredit the work of a critical author with power: 1. Non-academic 2. Antisystem 3. Communist 4. Populist 5. Pro-Russian 6. Anti-Semitic. Please, Spies and Minions: Have a little more imagination!”