Police began a race hate investigation last night after an announcement was broadcast in a supermarket ordering black people to get out.

A man's voice was heard calmly saying over the public address system: 'Attention Wal-Mart customers - all black people leave the store now.'

The demand caused an outcry among shoppers at the store in Washington Township, New Jersey.

Officials at Wal-Mart, which is America's biggest store chain, were reviewing security tapes yesterday trying to discover who hijacked the intercom to make the message on Sunday evening.

Detectives believe a racist employee may be responsible.

Witnesses told the Courier-Post newspaper that customers and store employees looked stunned. Management later apologised.
Company spokeswoman Ashley Hardie says the incident was 'unacceptable.' The retailer is looking to prevent it from happening in the future.

Washington Township police and the Gloucester County Prosecutor's Office also are investigating.

Wal-Mart bosses apologised for the 'unacceptable' incident on Sunday evening, but shopper Sheila Ellington, who was in the store when the announcement was aired, has vowed she will never return.

'In 2010, I want to know why such statements are being made. It flies in the face of what we teach our kids, and that's tolerance,' she said.

'I can't believe it in this day and age,' said Patricia Covington, another customer. 'Wal-Mart needs to be more responsible.'