The force said the defendant had self-defined their ethnicity as “any other”.
It added criminal proceedings were active and urged the public not to speculate while investigations continued.
GMP said the suspect had been charged with two counts of rape of a girl aged under 16, one count of sexual assault and one count of assault by penetration.
It is alleged the suspect had previously been in online contact with the girls before meeting them.
Both are being supported by specialist teams as officers continue to investigate the full circumstances.
GMP said it was not looking for anyone else in connection with this incident.
Ch Supt Helen Critchley, Bolton district commander, said: “This is a deeply concerning report, and our priority is supporting the two young girls and their families at this traumatic time.
“We have acted quickly since this was reported to us in the last 48 hours, and we’ve been using all available resources to understand what has happened and help this case progress through court.”