In January the Sheaf House in Bramall Lane erected the wooden gazebo-style shelter in the pub's large beer garden. Owners Enterprise Inns thought that, as the structure was portable and not attached to the building itself, it did not need planning permission and would not prove a problem.

But council planning officials say that as the pub is a listed building such a shelter would need permission and, even if the owners had applied, they would have been unlikely to get the go-ahead.

If enforcement action is taken the shelter will be removed within the next month.

Landlady Jayne Tomlinson said: "They're forcing us to take it down. Apparently as it's a listed building you can't do any alterations to it, but the gazebo isn't attached to the building – it's on a patio where the tables are.

"There's nowhere for our customers to smoke now and we're worried it's going to have an effect on the business.

"This is the biggest beer garden in Sheffield and the gazebo looks lovely. It's not unsightly or anything; it fits in really well with the area."

Planning officers, however, disagree. In a report to go before the council's south and east area planning and highways board on Monday officers recommend that enforcement action should be taken and, if necessary, legal proceedings begun in order to remove the gazebo.

In the report, officers argue that the structure detracts from the character of the Grade II listed building and could cause a "nuisance to nearby residents".

They say the "unauthorised" structure "is located on the southern side of the listed building and has a negative impact on the setting of the listed building... A further application is therefore not encouraged and it is considered that there is limited scope for a smoking structure due to the sensitivity of the site."