Police figures have revealed muggers could be behind a rise in allegations of gang rape in London.
Half of sex attackers are know to the victim
There have been reports of at least one group sex attack every day for the past year, a Scotland Yard study showed.
Two-thirds of suspects had convictions for theft and 50% were involved in street crime in the previous 12 months.
The figures show the assaults concentrated in the boroughs of Brent, Ealing, Hackney, Lambeth, Southwark and Westminster.
The attackers were aged mainly between 15 and 21, and the rapes took place outside and late at night - suggesting the assaults are linked to young robbers.
Police believe disrespect for women, who are often known to the attackers, and ignorance of what is "right and wrong" in sexual affairs, lie at the heart of the crime.
Half the victims were under 21, 75% under 30 and in about 50% of cases the attackers were known to the victims.
More than half the assaults involved three or more attackers.
About 70% of victims were attacked in "outdoor locations", often near main roads.
Women and girls of white or European appearance accounted for 59% of victims with 28% of victims described as African or Caribbean.
Suspects of African or Caribbean backgrounds were identified in 49% of attacks or allegation of assaults and 13% were committed by men of Indian or Pakistani appearance.
But Scotland Yard said youths from other ethnic groups, including whites, were involved in the gangs, suggesting that the attacks were linked to patterns of youth crime rather than simply race.
Commander John Yates, who has responsibility for the Metropolitan Police's Operation Sapphire unit that investigates sex crimes, told BBC Radio 4's Today programme: "It is not the ethnicity that counts here, it's the way we treat the victim.
"We feel the ethnicity issue is a societal issue, it's about family upbringing, code of morals etc."
Fall in recorded offences
Tony Sewell of the Voice newspaper agreed.
"I think the black community and other communities have got to do more in terms of taking up responsibility for those children," he said.
On Thursday Met Commissioner Sir John Stevens said actual recorded offences of group
rapes had fallen by 14% in the year December 2002 to November 2003 compared to the previous year.
In a letter to the Daily Telegraph he said: "Because we consider rape so serious and damaging a crime, we are putting more resources than ever before into both intelligence-gathering and dealing with these offences."