'We've got now hundreds of men, Pakistani men, who have been convicted of this crime - why are we not commissioning research to see what's going on?'

Lord Macdonald of River Glaven said he believes this is no longer the case, with recent successful prosecutions showing the "so-called taboos" no longer exist.

He added that all communities need to recognise it is a "profoundly racist crime".

The Liberal Democrat peer's remarks came after 18 people were convicted of or admitted offences in a series of trials related to child sexual exploitation in Newcastle.

Newcastle joins a growing list of English towns and cities where sex rings have been exposed, including in Rotherham and Rochdale.

Lord Macdonald, an ex-director of public prosecutions, told BBC Radio 4's Today programme: "I think there has been in the past a reluctance to investigate a category of crime that people might believe attaches to a particular community in circumstances where men may be targeting young women..."

Presenter John Humphrys, intervening, said: "In other words, we're talking about - by and large - Muslim men who have been targeting white girls?"

Lord Macdonald said: "Yes, exactly."

Mr Humphrys added: "In other words, we've allowed political correctness - if that's the right expression - to interfere with the course of justice?"

Lord Macdonald replied: "I think that's no longer the case and I think the fact that these sorts of cases are now being brought successfully demonstrates that those sorts of so-called taboos no longer exist - but I don't think any of us can pretend that in the past these cases have been examined as rigorously as they might have been."

He added he hopes this has changed, noting: "There's obviously a serious issue about the way young women are regarded in these cases - regarded as trash, regarded as available for sex, and this seems to be a recurring theme - and I don't think anyone thinks now we've got it.

"This is a major problem, it's a major problem in particular communities and it has to be confronted not just by law enforcement but by communities themselves."

Lord Macdonald said he expects more cases, adding he is sure there are ongoing investigations.

He said: "I think it's a real wake-up call for communities. Not all sex crime takes place in a single community, of course we know that, that's obvious.

"But there is a particular issue about some men in some communities who feel these young girls are trash who are available for sex.

"We all know that, we've seen it in this case, we've seen it in other cases, we know it's going on as we speak.

"Law enforcement has a response, the police have a response, prosecutors have a response, judges have a response, but communities need a response themselves."

Shadow women and equalities secretary Sarah Champion said there is a need to acknowledge that the "majority of perpetrators have been British-Pakistani" in the towns where such grooming cases have occurred.

The Labour MP for Rotherham, who called for more Government research, added that the lack of action is because people are "more afraid to be called a racist than they are afraid to be wrong about calling out child abuse".

She told the same programme: "We've got now hundreds of men, Pakistani men, who have been convicted of this crime - why are we not commissioning research to see what's going on and how we need to change what's going on so it never happens again?"

Ms Champion said every time she speaks about the issue, the level of Islamophobia increases, adding: "The far right will attack me for not doing enough, the floppy left will have a go at me for being a racist.

"But this isn't racist, this is child protection and we need to be grown-up about this and deal with it."

Ms Champion said the prosecutions and convictions of grooming gangs are "predominantly Pakistani men", adding: "If it was people from a particular town that was doing this crime across the country, if it was people from - I don't know - a motorbike gang doing this, we'd recognise that as an indicator and we'd deal with it - but we're just not dealing with it."

Asked why, Ms Champion said: "I genuinely think it's because people are more afraid to be called a racist than they are afraid to be wrong about calling out child abuse.

"I know in Rotherham I've met frontline social workers who, when - we're talking 10 years ago - they were trying to report this crime, were sent on race relations courses, they were told they were going to have disciplinary action if they didn't remove the fact they were identifying the person as a Pakistani male.

"This is still going on in our towns now, I know it's still going on but we're still not addressing it."

Northumbria Police Chief Constable Steve Ashman said men from a wide range of communities have been arrested by his force and convicted, including white men, Turkish men and Pakistani men.

He told the BBC: "I think the fundamental issue here is, somewhere along the line, in some communities, we've got to the point where it's acceptable for people to behave in this manner and that's where we need to focus the efforts if we're going to prevent this happening in the future.

"It has to be driven out in terms of its social acceptability."