The supermarket chain says its full-year profit will not be more than £1.4 billion.
That is substantially less than expected, analysts had predicted profit between £1.8 and £2.2 billion.
This latest profit warning comes as Tesco is being investigated by the Serious Fraud Office after admitting earlier this year it had overstated its profits by 264 million pounds.
That led to the resignation of the then Chairman and a number of other top bosses.
The Evening Standard’s Jamie Dunkley joins the Evening News with a business update.