Published Thursday, 12 September 2013
Fermanagh and South Tyrone representative Phil Flanagan. (© Presseye)
Fermanagh and South Tyrone MLA Tom Elliott lodged the complaint on Tuesday over a remark Mr Flanagan made about him on the social media site last year.
Referring to the flag row at Belfast City Hall, the Sinn Féin representative wrote: "I'm not sure who the biggest clampit is. The current leader of the UUP or his predecessor."
Mr Elliott said he accepted "the general debate and cut and thrust of politics" but had decided to notify the Standards Commissioner Douglas Bain.
He told the Impartial Reporter: "Given the unreasonable and demeaning language used by Mr Flanagan by referring on a personal basis to Mr Mike Nesbitt and myself as 'clampits' I suggest that he breached the code of conduct for members of the Northern Ireland Assembly."
The code of conduct instructs assembly members to act in a manner that is conducive to good relations and that discourse should be "kept in context and not extend to individuals being subjected to unreasonable and excessive personal attack".
This is the second time a complaint has been made about the politician after he took to Twitter.
In July, Mr Flanagan reposted a joke about the Duke and Duchess of Cambridge on the social site ahead of the Royal baby.
It sparked the launch of an investigation by the Standards Commissioner, after the Fermanagh and South Tyrone representative shared the remark with his 3,600-plus followers.
Mr Flanagan apologised for his "split second error of judgement", saying he had "misconstrued the meaning".
The MLA could face sanctions if he is found to have breached Assembly rules.
© UTV News