The huge scale of diplomatic cables unearthed by WikiLeaks has been revealed in a new book.

The WikiLeaks Files analyses some of the 2.3 million cables and other US State Department records so far published.

Around two billion words have been published - described by founder Julian Assange as a "stupendous and seemingly insurmountable body" of internal state literature.

The files published by WikiLeaks have caused huge controversy and embarrassment to the United States government over its activities across the world.

In a foreword to the book, Assange - who is trying to avoid being extradited to Sweden to be questioned about a sex allegation because he fears being taken to the US - details the anatomy of the US empire.

He describes how radio and satellite antennas "scrape the air" in scores of countries, disgorging diplomatic cables or "mass-intercepting" mobile phones.

From his office in the Ecuadorian Embassy in London, where he has been living for the past three years, Assange writes that the US State Department puts a friendly face on the empire, "concealing its underlying mechanics".

He says: "This book begins to address the need for scholarly analysis of what the millions of documents published by WikiLeaks say about international geopolitics."

He claims there has been an "unprecedented growth" in American official secrecy, and in the evolution of US power following the so-called war on terror.

In one of the chapters, WikiLeaks investigations editor Sarah Harrison offers a guide to using the cables.

The WikiLeaks Files is published by Verso.