Three teenagers charged over the alleged gang rape of a young woman at a pizza shop in Sydney's south west have been granted conditional bail in a children's court.

Key points: Defence lawyer for 17yo males argued they should be granted bail because they were young, had no prior convictions

Defence lawyer for 17yo males argued they should be granted bail because they were young, had no prior convictions Crown prosecutor alleged one of the accused told the woman to "drop these charges" on the street

Crown prosecutor alleged one of the accused told the woman to "drop these charges" on the street Youngest accused, 15, is an Iraqi refugee who has only been in Australia for six months

Police say the 18-year-old was drugged at a pizzeria in Lugarno in October, before a 38-year-old man, and two boys, aged 17 and 15, repeatedly raped her.

They are all charged with aggravated sexual assault in company and deprivation of liberty.

Another 17-year-old boy — known to the young woman — is accused of being an accessory before and after the alleged rape.

In Parramatta Children's Court on Monday, the Crown prosecutor, Peter Clayton, opposed bail for each of the teenagers, stating the matter was "very serious".

He told the court that if released on bail, the boys might try to interfere with the investigation or witnesses, or attempt to intimidate the victim.

Accused allegedly told woman 'drop these charges'

Mr Clayton referenced a chance meeting between one of the 17-year-old boys and the victim in Parramatta in December, where the teenage boy allegedly told the woman to "drop these charges".

Mr Clayton told the court the teenager did not stop until the woman waved down a police car.

The defence counsel for the two 17-year-old males, Elizabeth Nicholson, argued the teenagers should be granted bail because of their young age, the fact they had no prior convictions, and the weakness of the prosecution's case.

She told the court the deprivation of liberty allegation was unsubstantiated, and challenged the sexual assault charge, describing it as one of "a number of difficulties in the Crown's case".

"[It does not seem] that during the sexual intercourse she conveyed to any of the persons that she did not want to engage in sexual intercourse," she said.

Ms Nicholson told the court that when the 18-year-old called her friend after the alleged attack, she did not suggest she had been sexually assaulted, instead saying she had taken something and felt unwell.

"The complainant willingly, it seems, took cannabis … there is no mention of any other substance in the toxicology report," Ms Nicholson said.

She also referred to intercepted calls between the accused offenders obtained over a number of months.

"It is notable that there is no suggestion in any of these phone calls … there was anything that constituted any type of admission to non-consensual sexual intercourse," Ms Nicholson said.

While the Crown accepted the 17-year-old boy accused of being an accessory to the rape had consensual sexual intercourse with the woman, it opposed bail, saying the boy had played an "integral role in the participation of the event".

Youngest accused is a refugee

The Crown prosecutor also opposed bail for the 15-year-old boy, saying he was a flight risk because he had only lived in Australia for six months.

The boy's lawyer, Rebecca Dunlop, told the court he was a refugee from Iraq.

"The Australian Government has formed the view he is a legitimate risk of persecution if he returns to his jurisdiction," Ms Dunlop said.

"He is not afraid of the consequences, because the prosecution case against him is weak."

The 15-year-old boy's mother cried in court during the proceedings.

Bail granted, with strict conditions

Magistrate Terry Murphy granted bail to each of the teenagers with a list of stringent conditions.

They include reporting regularly to police, not contacting the victim directly or indirectly, not contacting each other, surrendering passports, and staying at their houses unless supervised by a parent.

The 15-year-old boy was also granted permission to attend school.

The three teenagers will appear in court again on Friday.

The 38-year-old man, who is also accused of holding the alleged victim captive for a period of time after the attack, will face court again in March.

When he appeared in Liverpool Court last Friday, he did not apply for bail and it was formally refused.