Sheffield Council has been forced to apologise after flying a Welsh flag above the Town Hall on St Patrick's Day.
A red dragon was seen flying over the city centre yesterday as people took part in the Irish celebrations.
The council has admitted mixing up the flags and said sorry for any offence caused.
Its mistake came a day after Wales beat Ireland to win the Six Nations rugby trophy.
In an initial statement, Sheffield Council said: "While we're at it, we would like to congratulate Wales on their fantastic victory in the Six Nations at the weekend and wish everyone a Happy St Patrick's Day, too."
Subsequently, the council apologised for putting up the wrong flag, as well as for the tone of its earlier comment.
A spokesman said: "We are very sorry that the Welsh flag was raised in error yesterday rather than the St Patrick's flag. We are also sorry for any offence caused by our earlier statement."
The error has left many social media users confused.
Helen Shipley tweeted: "Er, is there a particular reason the WELSH flag is flying above #Sheffield Town Hall on #StPatricksDay?"
Another user said: "Sheffield flew a Welsh flag on St Patrick's Day, as if we couldn't troll the Irish enough!"