Belfast Lord Mayor Martin Morgan has vowed to boycott all public functions attended by British government minister John Spellar.
The move is a protest against Mr Spellar's decision to allow two British soldiers convicted of murdering a Belfast teenager to remain in the British army.
Mr Spellar sat on an army board which decided to allow James Fisher and Mark Wright to return to the Scots Guard regiment after serving just three years of their life sentences.
Last week, Mr Spellar rejected a request from the family of the victim to kick the two convicted murderers out of the British army.
Wright and Fisher were convicted of murdering Peter McBride, an 18-year-old father-of-two, as he ran away from British soldiers in north Belfast in 1992.
The court rejected the pair's claim that they only opened fire because they thought Mr McBride was carrying a coffee-jar bomb.
A Court of Appeal in the North ruled in June that the army board which Mr Spellar sat on had not produced the exceptional circumstances needed to justify the soldier's retention in the army following their release in 1998.
Mr McBride's mother, Jean, met Mr Spellar last week to discuss the ruling, but she walked out of the meeting when it became clear that he would not take action against Wright and Fisher.