The Irish language portion of a sign erected by the Mid Ulster District Council has been spray painted over within days of it being erected.
The new sign had been put in place at Portglenone Bridge to mark out the entrance to the council district, which was established in April 2015.
Ahead of the establishment of the district authority, a vote by the council - which has a nationalist majority - opted to place Irish above English on its own signs and logos.
The vandalism was noticed by Sinn Fein councillor Sean McPeake, who told the Belfast Telegraph it came to his attention on Christmas Eve.
"The new signs are marking out the new district council area, where the one council area ends and where the other one begins, so it’s gateway signage for the district," he said.
"There was a number of new signs erected around the district in the last few days. It is just disgusting to see it defaced so quickly."
Cllr McPeake said he believed the issue has to be taken seriously.
"I do believe it is a hate crime," he said. "It is not as if other signs are being attacked; this sign is being attacked because there is an Irish language on it and it is the Irish language element that has been defaced."
The PSNI confirmed it had received a report of damage caused to a sign in the Portglenone area, and that enquiries are ongoing.
Irish-language signage has previously proven a controversial point in the Mid Ulster council area.
After the Tullaghoge Fort ancient site reopened in the summer of 2016 following a £500,000 redevelopment, the Irish language portion of its sign was targeted by vandals on four separate occasions.
In September of this year a row broke out over a scheme in place that allows members of the public to apply to have their signs in Irish and English.
At the meeting of the council's environment committee, members were asked to consider the street signage of a new residential development.
DUP councillor Clement Cuthbertson proposed that residents should be asked to make a contribution to the cost of dual language signage. The proposal was put to a vote, and with three voting for and 10 against, the proposal fell.
Accusing the council of following the route of "non-inclusive politics," Mr Cuthbertson said that "the dual language street signs had been forced amongst the minorities in Mid Ulster".