A convicted child sex offender remains behind bars, accused of luring a seven-year-old girl from a Sydney street and into an abandoned property and partially removing her clothes.

Police allege 34-year-old Christopher Irwin targeted the young girl outside her Macquarie Fields home yesterday afternoon, grabbing her by the hand before leading her to the vacant property.

It is believed two boys who were sitting on their front verandah at the time saw the exchange and ran to alert the girl's grandmother.

A convicted child sex offender remains behind bars, accused of luring a seven-year-old girl from a Sydney street and into an abandoned property and partially removing her clothes. (Supplied)

The alleged seven-year-old female victim claimed to have been lured into the abandoned home after Christopher Irwin, 34, promised to show her something 'cool'. (Supplied)

"The boys tried booting the door in. We ended up yelling out, ringing the police," an adult witness, who helped the boys rescue the young girl, told 9News.

"It was the quietness, when we were banging on the door, that (was) my biggest fear because it seemed like it was probably less than five minutes, but it seemed like forever.

"Then, I heard her voice - like a muffled sound - (and) I hear 'nanny'."

A witness to the incidents told reporters that two boys noticed the interaction and alerted the girl's grandmother. (9News)

Authorities also allege that when the girl was released, her clothes had partially been removed.

Irwin today faced Parramatta Bail Court on four charges of taking a child and remaining in a building with intent to commit an indictable offence.

The court heard he told the alleged victim, "be quiet and I'll wait for your nan to go, and then I'll let you go."

Irwin has been refused bail after a magistrate described the allegations against him as disturbing and concerning. (Supplied)

The adult witness also said the little girl told her grandmother she was "tricked" by the alleged offender.

"She was just like, 'nanny he told me he was going to show me something cool and then he took me inside and closed the door and there was nothing cool - he lied to me'," she told 9News.

Despite that, Irwin's girlfriend claims he told her a different version of the incident.

It is also alleged the 34-year-old tried telling his girlfriend a different version of the incident, suggesting he had been drunk and arrested due to a fight. (9News)

"(He was) telling me just that he was drunk and he'd been arrested and he's been in a fight with a stranger," she said.

The Sydney court also heard Irwin has a prior conviction for accessing child pornography and has a mild intellectual disability.

His bid for bail during the hearing today was refused after a magistrate described the allegations against him as disturbing and concerning.