A warning urging coronavirus restrictions to be followed, especially when watching sport in bars and pubs, has been given by Hull City Council.
Councillor Daren Hale said people using all the city's businesses had to behave "appropriately and responsibly".
It comes as The Euro 2020 tournament kick-off expects to bring more fans to venues.
The easing of restrictions on 17 May allowed venues to reopen indoors as well as outside.
Rachel Stephenson, head of public protection at Hull City Council, said: "One of the biggest challenges businesses face is managing customers who fail to respect guidelines and the systems that have been put in place."
Hull City Council leader Mr Hale said: "For many of us, the opportunity to share a drink with friends in a bar or visit the theatre has been invaluable following months of difficult lockdown and isolation.
However, he warned customers "we all need to play our part" in order to keep stricter restrictions at bay.
The final stage of lifting lockdown in England is due to take place no earlier than 21 June. A decision is expected on Monday.
There have been 80 new coronavirus cases in Hull in the seven days up to 6 June.
This is a rate of 30.8 per 100,000 of the population an increase of 43% on the previous week.
Hull City Council said it was working with the Health and Safety Executive to visit and support local businesses.
Anyone who believes that a venue is failing to implement appropriate measures or act responsibly can contact the council's Public Protection Team, it said.