The GMB union protested over the treatment of Amazon workers outside Old Trafford in Manchester on Tuesday.
Tories and Amazon bosses were hosting an Amazon Marketplace New seller event inside the Manchester United ground.
The protest came after a former worker at the Amazon warehouse in Staffordshire claimed they had to use a bottle because the toilets were too far away. The GMB said workers reported that they feared the sack if they were gone too long.
And delivery drivers have described working conditions as “slave labour”.
Mick Rix, GMB national officer, said, “Amazon execs are coming to Manchester celebrating their latest money making scheme.
“We want to know why workers report ‘hellish’ working conditions so pressured they have to urinate into plastic bottles.
“Companies like Amazon should be treating staff with respect, not treating them like robots.”