"The World Backwards" by Roberto Vannacci, 54, a general who served in Afghanistan and Iraq and now heads Italy's Military Geographical Institute, was self-published this month without the knowledge of the army, officials said.

"The personal ramblings of a general, even if still in service, should not be used in any way to polemicise Defence and the Armed Forces," said Defence Minister Guido Crosetto in a statement.

Crosetto is one of the co-founders of the right-wing party Brothers of Italy, led by Prime Minister Giorgia Meloni.

The general had "expressed personal opinions that discredit the Army, Defence and the Republican Constitution," for which a "disciplinary examination" will be launched, the minister said.

Among various opinions expressed in the book sold on Amazon.com, Vannacci says homosexuals are not "normal" and rails against the "dictatorship of minorities," taking aim at feminists, environmentalists, people of colour, and immigrants.

He describes Italian star volleyball player Paola Egonu, who is black, as "Italian by citizenship, but it is clear that her features do not represent Italian-ness".

Meloni's right-wing government puts a strong emphasis on traditional family values and the premier has herself voiced opposition to the "LGBT lobby".