Salim Mehajer has been taken to Westmead Hospital after a car accident prevented him from attending the first day of his trial for allegedly assaulting a taxi driver.

Mr Mehajer's lawyer Brett Galloway told magistrate Vivien Swain on Monday his client had been involved in a "relatively serious" crash on the way to the Downing Centre Local Court.

Mr Galloway said he had seen footage of Mr Mehajer on a stretcher being loaded into an ambulance bound for hospital.

It is understood two cars including Mr Mehajer's white Mercedes were involved in the crash in Delhi Street, Lidcombe, shortly before 9am on Monday.