A Canberra carer accused of repeated sex with his 14-year-old foster daughter has gone on trial in the ACT Supreme Court.

Prosecutors say the teenage girl became ‘‘infatuated’’ with her 35-year-old foster father, who cannot be named, and told friends she was in love with him.

The pair allegedly began having sex in 2010, while the foster mother was away from the home.

The court heard the girl had come home from school upset, following an argument at school.

The Crown alleges the foster father began to comfort her, then kissed her on the lips.

The girl is said to have recoiled, and pulled away, but the man allegedly kissed her again, taking her clothes off, and performing oral sex on her.

Prosecutor Anthony Williamson said the man then attempted to have sex with her.

That was allegedly the start of a sexual relationship that went on between 2010 and 2011, while the girl was 14 and 15.

The foster father is now facing 12 charges and went on trial before a jury in the ACT Supreme Court on Friday.

‘‘We say that the accused felt sexual urges towards [name removed] who was at the time an attractive teenage girl,’’ Mr Williamson told the jury.

The Crown says the man warned her that if anyone found out about their relationship, she should ‘‘deny, deny, deny’’.

It is alleged the man emotionally blackmailed the girl, telling her he would kill himself if she told anyone.

The man is fighting the charges and his barrister James Sabharwal told the jury that they must take great care when listening to the girl’s evidence.

Mr Sabharwal asked the jury members to put their views about the nature of the allegations to one side.

‘‘This is not the place for you to express those views,’’ Mr Sabharwal said.

‘‘Your duty in this case is to assess the evidence and do so fairly.’’

The trial, which the Crown warned was not going to be ‘‘particularly pleasant’’, continues on Friday afternoon before Justice Richard Refshauge.