The Union of Shop, Distributive and Allied Workers (Usdaw) is calling for shoppers to remain calm during the Black Friday sales following an increase in abusive behaviour towards staff during the pre-Christmas sales.

Union leader Paddy Lillis has called for people to “keep their cool” with shop workers, following abuse on the discounting day in previous years.

A Usdaw survey of shopworkers in 2014 revealed a two-thirds increase in incidents of threats, violence and verbal abuse against retail staff on Black Friday, so the union set out to minimise any future abuse.

Lillis said: “Our members have had real concerns about Black Friday. After two years of unprecedented scenes of mayhem in some stores, as bargain hunting turned into a frenzy, we discussed safety issues with retailers.

“They responded positively by organising their events to maximise safety and security for staff and customers alike. Consequently, recent years have been quieter and more respectful, but we continue to monitor the situation.

“Violence, threats and abuse against shopworkers are already worryingly high, interim figures from this year’s Usdaw survey of over 4,000 shopworkers suggest there’s been a big jump in incidents, with violence against shopworkers up 25% since last year.

“Usdaw and retail employer organisations have been jointly calling on the government for additional legal protections to prevent attacks on shopworkers and ensure that violent criminals are prosecuted.

“Unfortunately, Conservative ministers have not yet responded to the evidence received in their own consultation, which was debated on the final sitting of Parliament. However, Usdaw is very pleased that Labour’s manifesto promises to legislate for shopworker protection.

“Around 400 retail staff are violently attacked every day, with many more threatened and verbally abused. It is time to say enough is enough and only Labour has pledged to deliver much-needed protections.

“My Black Friday message to shoppers is clear. Enjoy your bargain hunting, keep your cool and respect shopworkers.”