Workers at supermarket giant Asda have been stabbed, punched and threatened with syringes by customers, according to new research.
The GMB said a survey of 1,000 of its members at the company revealed that one in three had been attacked at work.
Delivery drivers said they have been chased by people in cars and confronted by customers in the nude, while store workers have had watermelons and joints of gammon thrown at them.
The survey, which will be discussed at the GMB's annual congress in Bournemouth today, also found that three in five respondents said they had suffered injury or illness at work
Nadine Houghton, GMB national officer, said: "These incidents are horrifying - no-one should have suffer this kind of abuse and violence at work.
"But this situation is only going to get worse as staff hours are slashed, leaving less people in store and those who are there more vulnerable."
An Asda spokesperson said: "Unfortunately, like all retailers we have seen an increase and violence and aggression towards our colleagues during the last few years.
"The safety of our colleagues is a primary concern, which is why we have invested over £30 million during the last three years to upgrade the CCTV systems in stores.
"We have also provided colleagues with body-worn cameras, hired extra security guards in certain stores and amended store opening times when required.
"We work with all of our colleague representatives in the important area of colleague security and also back calls for violence or abuse against retail workers to be made a standalone criminal offence in all parts of the UK and hope this is a priority for any incoming government."
