Boy allegedly sexually assaulted in Sydney train station toilet

A man is in custody tonight after a teenage boy was allegedly sexually assaulted at a Sydney train station.

A 15-year-old boy was allegedly assaulted in a toilet on the Country Concourse at Central Station in the CBD at about 3pm on Saturday.

The teenager told his mother, who contacted police.

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NSW Police said they were able to pinpoint the man allegedly responsible on CCTV walking along one of the platforms and in the station.

Officers then searched a unit in Mortdale in the city's south.

The occupant, 75-year-old Bryce Grainger, was arrested and led down his driveway in handcuffs.

Investigators also seized clothing and electronic devices, as his shocked neighbours watched on.

The pensioner was taken to Kogarah Police Station and charged with sexual assault offences.

He was refused bail but did not appear in court today, so he remains in custody.