"I'm very pleased that the Court of Appeal has today given clear guidance in respect of sentencing sexual offences of this nature.
"The law is clear that children under the age of 13 are incapable of giving consent to sexual activity, and I hope that today's sentence sends out a strong message to anyone who commits terrible crimes such as these - that you can expect to spend a substantial time in prison."
Baljit Ubhey, Chief Crown Prosecutor for Thames and Chiltern Crown Prosecution Service (CPS), said: "We supported the Attorney General's decision to refer this case as one that had attracted sentences that were unduly lenient.
"I welcome today's ruling from the Court of Appeal to increase the sentences.
"Roshane Channer and Ruben Monteiro took advantage of a very young girl and, although they pleaded guilty at the earliest opportunity, needed to be punished for their crime.
"The original sentences of 40 months imprisonment in no way reflected the severity or seriousness of their crime. Today's increased sentences do.
"The CPS takes all allegations of rape seriously and has specialist rape prosecutors who have expertise in dealing with sexual offences cases.
"We work with the police and the courts to ensure that victims are given the best possible support.
"Cases of rape and other serious sexual offences are among the most difficult cases that we deal with and need to be dealt with very sensitively.
"The increased sentences given today recognise the severity of the offence and the vulnerability of the victim.
"I hope that today's increased sentences provide the victim with some measure of justice that will help her put this terrible episode behind her and move forward in her life.
"We will continue to vigorously prosecute offenders who target young and vulnerable victims."