Restaurant chain Wagamama has apologised after a manager threatened staff with disciplinary action if they called in sick over Christmas.
A note on a rota on a London branch of the restaurant said it was up to junior members of staff to find colleagues to cover if they were unable to make their shift.
The chain said in a tweet it was an "isolated incident" and was "strictly not company employment policy".
The note read: "No calling in sick! May I remind you that if you are unable to come for your shift it is your responsibility to find somebody to cover your shift (as per contract and handbook).
"Calling in sick during the next two weeks will result in disciplinary action being taken."
It provoked outrage on social media when it was shared by Unite Hospitality, a division of the the UK's largest trade union Unite.
In a series of tweets, Wagamama UK wrote: "Following reports of a notice posted in our North Finchley restaurant we can confirm this was an incident and is strictly not company employment policy.
"The manager involved feared team member shortages over the festive period and regrettably decided to take this highly unusual approach.
"As a company we treat all our team with the greatest respect and understand and appreciate the hard work they all do.
"We sincerely apologise for what has happened and we wish all our team members and customers a very merry christmas and a happy new year."
Wagamama has two sites in Sheffield with restaurants in Meadowhall and Leopold Square.
Brian Simpson, a spokesman for Unite Hospitality, is concerned the incident is not a one-off.
He said: "To threaten workers with disciplinary action for being sick is not just morally reprehensible, it may be unlawful under the Health & Safety act and Equality Act as it discriminates against those with long-term physical and mental health conditions."
He added: "Although this is an extreme example, we do believe that the issue of sick staff being pressured to come into work is systematic across the company.
"We have heard from workers across the country that conditions have gotten worse and worse.
"We want to sit down with senior managers and see how we can improve conditions."
The organisation is currently running a campaign to make sure hospitality staff get proper rest breaks, paid transport past midnight and a minimum hour contract.
It is also campaigning for the living wage, equal pay for young workers and a campaign to get employers to implement a proper anti-sexual harassment policy.