The probe has widened significantly since nine Asian men were convicted in May of the systematic grooming and sexual abuse of white girls in Heywood and Rochdale.
Greater Manchester Police announced last night that a further nine men have been charged in connection with the alleged sexual abuse of one teenage girl in Rochdale between 2008 and 2009.
Officers in the region are also investigating three other groups of men alleged to have sexually abused a series of teenage girls, as well as "numerous" smaller cases involving one alleged victim who says she was abused by one or two men, the Manchester Evening News reported.
The force declined to say precisely how many cases it is investigating but it confirmed that there are now about 400 officers working full-time on child sexual exploitation and other sexual offences.
Detective Chief Superintendent Mary Doyle, head of Greater Manchester Police's public protection division, said: "There are currently a number of child sexual exploitation investigations under way across the force, which range from individuals up to large groups of offenders that are loosely connected to each other.
"Some of these investigations have arisen from historic allegations and some are based on new complaints.
"We now have a much better understanding of the signs to look for, plus there have been significant improvements in the sharing of information between agencies. Also, the widespread publicity surrounding recent cases has ensured that victims, witnesses, carers and the wider community are much more alive now to the threat of child sexual exploitation.
"Child sexual exploitation is now one of the force's top priorities and we are absolutely committed to ensuring it gets the resources that it deserves."
Meanwhile, Keir Starmer, QC, the Director of Public Prosecutions, has said that a generation of girls had been betrayed by the justice system's flawed approach to sexual exploitation.
He has ordered a major overhaul of the Crown Prosecution Service's response to sex grooming, with the aim of increasing the number of convictions.
Mr Starmer admitted that a failure to understand the nature of abuse by police, prosecutors and the courts meant that men who groomed teenagers for sex had escaped justice for decades.
"In a number of cases presented to us, particularly in cases involving groups, there's clearly an issue of ethnicity that has to be understood and addressed. As prosecutors we shouldn't shy away from that," he told The Times.
"But if we're honest it's the approach to the victims, the credibility issue, that causes these cases not to be prosecuted in the past. There was a lack of understanding."