A City councillor sparked a Twitter spat after he posted he would "punch a Lib Dem in the face" if he reached 500 followers.
Labour councillor Chris Sumpton, who currently has 526 followers, has insisted the tweet was only meant in jest after facing an angry backlash from rival party members.
But furious Liberal Democrat's are reportedly considering taking the matter further.
The Hull Daily Mail reports that the issue was raised during a full council meeting when Councillor Eliza Mann asked council leader Stephen Brady to condemn the tweet.
But the leader said he couldn't comment because wasn't familiar with the social networking site so didn't have the full facts.
Afterwards, Cllr Mann said: "It was a really nasty thing to find."
She added the party is seeking advice on whether to take the matter further on behalf of the Lib Dem group.
"It is insulting to every Lib Dem member in the city," she said.
Cllr Sumpton, who recently fought in a charity boxing match, defended his comment and said the tweet was "clearly a joke."
"I am now at 500 followers and no Lib Dem has been punched nor will they be. There was never any intention to do so. The thought that anybody could take this seriously shocks me."
He also criticised the Lib Dems for making so much of the tweet, teasingly adding their energies would be better focused on their policies.