Published Sunday, 30 September 2012
BNP leader Nick Griffin attended the Ulster Covenant event at Stormont (© Getty)
Mr Griffin used the offensive term in a tweet he published on Saturday.
SDLP Belfast City Councillor Nichola Mallon said she lodged a formal complaint with the PSNI after regarding the tweet as "incitement to hatred".
"The complaint I have lodged cites Part III of the Public Order (Northern Ireland) Order 1987, which deals with actions or words which stir up hatred or fear," she explained on Sunday.
Ms Mallon said the tweet by the MEP for North West England was inflammatory and sectarian.
"By using the language he used, he has also proven himself unfit for elected office and the authorities at the European Parliament should be taking advice on what action to take against him," she said.
Mr Griffin said he sent the tweet, which is still visible on his timeline, after receiving abusive messages from republicans.
Speaking to BBC Radio Ulster, Griffin said he would not be withdrawing his remark which was not aimed at Catholics in general.
In a statement a PSNI spokeswoman said: "Police have received a complaint regarding the matter and are investigating."
Tens of thousands of people took part in a parade through Belfast to mark the 100th anniversary of the signing of the Ulster Covenant.
The day culminated in a huge cultural festival staged in the grounds of Stormont to commemorate the 1912 proclamation against plans for Home Rule in Ireland.
A spokesman for the Orange Order said the event was open to the public and Mr Griffin was not their guest.
© UTV News