Sydney teen charged over elderly assault

An 18-year-old man has been charged with assaulting an elderly woman in her home in Sydney's west.

Police were alerted by alarmed staff at a Seven Hills bank after the 78-year-old turned up at the branch with serious facial injuries about midday on Wednesday.

Police believe she was assaulted at her Toongabbie home sometime between Tuesday evening and Wednesday morning.

Police arrested the man at his Toongabbie home just after 10am on Thursday and took him to Blacktown station.

He was charged with breaking and entering, wounding with intent to cause grievous bodily harm and committing a special aggravated indictable offence.

He was refused bail to appear in Blacktown Local Court on Friday.

The woman was taken to Westmead Hospital.