A man described as Britain’s most prolific rapist could have his sentence increased after the Crown Prosecution Service wrote to the attorney general saying Reynhard Sinaga should serve longer than 30 years in prison.

Sinaga, a 36-year-old mature student from Indonesia, was given a life sentence with a minimum tariff of 30 years by a judge at Manchester crown court last week. Suzanne Goddard QC told him it was “borderline” whether he should be given a whole-life term but decided that he should not be considered for release until he was 66, having been unanimously convicted by four juries of drugging and abusing 48 men while they lay comatose in his Manchester flat.

Greater Manchester police says it has evidence to suggest he may have raped 195 men between 2005 and 2017, when he was arrested.

The office of the attorney general, Geoffrey Cox QC, confirmed he had received a letter asking to review the sentence. The Guardian understands the letter came from the CPS, which thinks a higher minimum tariff or even a full life sentence would be more appropriate.

Under the unduly lenient sentence scheme, the attorney general has 28 days after sentencing to review the decision.

Sentencing him on 6 January, after four gruelling trials spanning a year and a half, Goddard said she considered whether she had the authority to ensure he was never released.

“Whole-life sentences are extremely rare and I understand that a whole-life order has never been made in a case other than one involving murder,” she said. The judge said she accepted evidence from a forensic drugs expert, Dr Simon Elliott, who said it would be easy to kill someone with GHB, the date-rape drug Sinaga is suspected of using to stupefy his victims.

“Whilst these offences collectively and individually are of the utmost seriousness, and in my view did involve a risk to life, given the evidence of Dr Elliot, the features of torture and violence are absent, and do not involve death or lasting serious physical injury. You are clearly well versed in the necessary doses and mercifully none of the victims suffered any lasting serious physical effects.

“The sole feature that would allow the court to contemplate the passing of a whole-life order would be the vast scale of your offending, which now involves 48 victims – some 23 in these two trials. This is in my view a borderline case, as described in the authorities, and as such I must therefore shrink back from passing a whole-life order. In my judgment, you are a highly dangerous, cunning and deceitful individual who will never be safe to be released but that is a matter for the Parole Board.”

The judge told Sinaga that a minimum term was not a fixed term, after which he would automatically be released, but the minimum time he would spend in custody before he could be considered for parole. She said: “It will be for the Parole Board to say at that time whether and if so on what conditions you are to be released. If and when you are released you will be subject to licence for the rest of your life. If you were to be in breach of any condition of your licence, that licence could be revoked and you would then be recalled to prison to continue to serve your life sentence in custody.”

Sinaga was convicted of 159 sexual offences: 136 counts of rape, eight counts of attempted rape, 13 counts of sexual assault and two counts of assault by penetration.

A Crown Prosecution Service spokesperson said: “The case of Reynhard Sinaga is unprecedented in CPS history and we took a range of factors into account when bringing each trial to court.

“A key consideration was the likely impact on sentence of bringing further prosecutions, and we are confident we did everything we could to ensure the court had adequate sentencing powers to see justice done in this case.”