Zizzi has launched an internal investigation after one of its restaurants was closed by police over reports staff had continued working while awaiting coronavirus test results.
According to The Guardian the Italian chain's site in Clifton, Bristol closed last Thursday but reopened on Monday following a deep clean.
All staff members involved are now self-isolating.
Avon and Somerset Police said: "We received a call on Thursday 29 October amid reports of two members of staff at Zizzi's restaurant in Clifton failing to self-isolate the previous day. Two officers from our Covid team attended and the premises was shut.
"We have made Public Health England and the local authority's environmental health team aware."
It is understood this is an isolated incident and is not in line with Zizzi policy across its estate.
A spokesperson for Zizzi told The Caterer: "We have clear Covid measures in place to protect the wellbeing of our customers and our teams, however on this occasion our strict protocols have not been adhered to. As soon as we discovered this, we acted decisively to voluntarily close the restaurant, with all team members self-isolating, and there is an ongoing internal investigation into the mistakes that were made."
Zizzi is owned by Azzuri Group, which also runs the Coco di Mama and Ask Italian brands.
The company was bought out of administration by investment management firm TowerBrook Capital Partners in July in a deal that saw 75 sites close with the loss of around 1,200 jobs.