A judge is facing criticism after she handed down a suspended sentence to a teacher found guilty of having sex with a pupil and said the 16-year-old girl had “groomed” him.

Stuart Kerner, 44, a former religious studies teacher, had sex with the girl at school and at her home when she was 16. Jurors heard he had sex with her at Bexleyheath Academy in south-east London, where he was vice-principal, the same week his wife miscarried their second child.

He later drove the girl to her home where the pair had sex, kissed and cuddled, Inner London crown court heard.

Judge Joanna Greenberg QC said the victim had become “obsessed” with Kerner. She told him: “Her friends described her, accurately in my view, as stalking you … There is no evidence you encouraged her in any way. There is no evidence you groomed her. If anything it was she who groomed you. You gave way to temptation at a time when you were emotionally vulnerable because of problems with your wife’s pregnancy.

“She was intelligent and used that intelligence to manipulate people emotionally. She was vulnerable and needy and had a troubled home life.”

The judge gave Kerner an 18-month suspended sentence. His name will go on the sex offenders’ register.

Jurors heard that he had told the teenager their relationship was “written in the stars”. He had shown her a condom he had brought into school and told her he would use it when she became too “irresistible”, the prosecution told the court.

Louise Pennington of the campaign group Everyday Victim Blaming said: “We are deeply concerned by the statements made by Judge Greenberg in sentencing Stuart Kerner for sexually abusing his 16-year-old student.

“The law is clear that a child under the age of 18 cannot consent to a sexual relationship with a teacher because of the power imbalance. All teachers know this. Yet Judge Greenberg has accused the child of ‘grooming’ her teacher and has mitigated Kerner’s responsibility because he was ‘emotionally fragile’ about his wife’s miscarriage.

“As is clear from Annex C of the guidelines on prosecuting child sexual abuse, a 16-year-old girl cannot ‘groom’ an adult.

“We will be reporting this case to the attorney general due to the low sentence.”

The attorney general’s office said on Wednesday it had received complaints about the sentence and will consider whether to refer to the court of appeal under the unduly lenient sentences scheme.

Holly Dustin, director of the End violence Against Women Coalition, said: “Judge Greenberg’s reported comments are astonishing in that they literally blame the young victim for his actions. The judge reinforces very negative myths about sexual violence, that the perpetrator was led on by the victim and that his wife’s pregnancy was partly to blame. Anyone in fact other than Kerner himself.

“This case shows how such deeply held prejudicial attitudes permeate the criminal justice system at all levels and raises serious questions about the adequacy of judicial training on sexual violence.

“It also highlights the need for schools and other institutions to prioritise girls’ safety from predatory men and to work with specialist sexual violence services in their community.”

Kerner, of Aylesford in Kent, was found guilty last month of two counts of sexual activity with a child by a person in a position of trust. He was cleared of four counts of the same offence and also acquitted of two counts of sexual activity with a child, which relate to the period when she was 15.

Government guidance says the offence of sexual activity with a child by a person in a position of trust “is principally designed to protect young people aged 16 and 17 who, even though they are over the age of consent for sexual activity, are considered to be vulnerable to sexual abuse and exploitation from particular classes of persons who hold a position of trust or authority in relation to them”.

On Wednesday, the court heard Kerner maintained his innocence despite his convictions. His defence lawyer, Edward Ellis, said that, on the night the jury gave its verdicts, Kerner was in such a state of shock that paramedics and mental health specialists were called in.

A pre-sentence interview with a probation officer also revealed that “as a result of these convictions, he had considered taking his own life”.

But the court heard that mobile telephone calls backed the girl’s account of his movements.

Greenberg said she believed the victim was “intelligent and manipulative” and “showed no compunction” about lying when it suited her. But the victim was also a vulnerable young girl and Kerner was in a position of trust, she said. “The law demands that you are the responsible adult and that you show restraint, and we know that you failed to do so,” she said.

Jurors had heard that Kerner took advantage of the “besotted” schoolgirl, who cannot be identified for legal reasons. In a video interview with police, played to jurors, the girl said: “It felt special. But, I dunno, it wasn’t really. And admitting that does kind of hurt.”