Campaigner Sarah Green from End Violence Against Women said the comments made by broadcaster Nick Ross in his book are "horrible".
It's really disappointing - more than that, it's horrible - that a reputable journalist like Nick Ross, with expertise associated with crime through Crimewatch, is trotting out with the same spurious myths about rape.
– Sarah Green, campaigner with End Violence Against Women
The former Crimewatch presenter, Nick Ross, said it "sickens and appalls" him that people could now assume he blames rape victims or "belittle what they suffer".
He said the Mail on Sunday had chosen to focus on a single chapter in his book which "touches on the highly emotive issue of rape".
In his statement, Mr Ross said: "For the record, lest it needs saying, and, as I make clear in the published extracts, anyone who suffers such a violating crime should be the centre of our concerns.
"As I write in the book, rape is one of the most defiling crimes and there is never excuse or justification for it."
He said the book cited research which found that many victims themselves do not regard what happened to them as rape, "even though in law it plainly was".
He continued: "In other words victims themselves plainly see gradations in rape: It has become sacrilege to suggest that there can be any gradation: rape is rape. The real experts, the victims, know otherwise."
Broadcaster Nick Ross has defended comments in his book in which he claims that "rape is not always rape".
He said: "Far from attacking victims the chapter explores why so few victims report rape, why so few prosecutions take place, and whether criminal courts are the best way of helping to deal with the appalling suffering caused by sex attacks."
In his book, Crime, Mr Ross said it had become "sacrilege to suggest that there can be any gradation: rape is rape".
Half of all women who have had penetrative sex unwillingly do not think they were raped, and this proportion rises strongly when the assault involves a boyfriend, or if the woman is drunk or high on drugs: they went too far, it wasn't forcible, they didn't make themselves clear...
For them, rape isn't always rape and however upsetting, they feel is a long way removed from being systematically violated or snatched off the street.