Britain: A Tory MP has been forced to quit his frontbench role after making comments on race in the Army
Shadow homeland security spokesman Patrick Mercer said he had met "a lot" of "idle and useless" ethnic minority soldiers who used racism as a "cover".
The former officer also told the Times that being called a "black bastard" was a normal part of Army life.
But Mr Mercer later said he "deeply" regretted any "offence" he had caused.
Of the English-born black men he knew in the Army, he told The Times: "They prospered inside my regiment, but if you'd said to them: 'Have you ever been called a nigger,' they would have said: 'Yes.'
"But equally, a chap with red hair, for example, would also get a hard time - a far harder time than a black man, in fact."
Mr Mercer, MP for Newark, added: "But that's the way it is in the Army. If someone is slow on the assault course, you'd get people shouting: 'Come on you fat bastard, come on you ginger bastard, come on you black bastard.'"
He also said: "I came across a lot of ethnic minority soldiers who were idle and useless, but who used racism as cover for their misdemeanours.
"I remember one guy from St Ann's (Nottingham) who was constantly absent and who had a lot of girlfriends.
"When he came back one day I asked him why, and he would say: 'I was racially abused.' And we'd say: 'No you weren't, you were off with your girlfriends again.'"
After the comments were published, Mr Mercer was asked by his party to resign his frontbench position and did so.
Mr Cameron said: "The comments made by Patrick Mercer are completely unacceptable and I regret that they were made.
"We should not tolerate racism in the Army or in any walk of life. Patrick Mercer is no longer a shadow minister."
He also said: "I was completely shocked when I read the remarks of Patrick Mercer."
He added that "racism is disgusting and has no part in any part of our society".
Labour MP Sadiq Khan said: "I find these comments shocking and most members of the public will find them outrageous."
But Leroy Hutchinson, a black former corporal who served with Mr Mercer for 12 years, said: "He never tolerated racism in the battalion and not a single one of his men would consider him to be racist."
Mr Hutchinson told the BBC: "In the forces... name-calling - whether you be black, white, ginger, red, brown - it is part of the establishment."
He added: "It's not meant and it doesn't come across from an individual as a racist comment. It's just part of the culture.
"When you wear that uniform, it is what goes on and it's been happening for a long, long time."
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