A SINN Féin councillor has made an impassioned online attack on Louise Minihan, the Dublin city councillor who defected from the party recently, and blasted "Comrades don't do this!"

Matt Carthy, a county councillor in Monaghan, has used his website to criticise his friend Minihan's decision to leave and pleaded with her to give up her council seat and give it back to Sinn Féin.

Carthy claimed on his blog that Minihan, who is godmother to one of his children, lied to him about leaving the party when he asked her about rumours that were circulating in the weeks before her departure. He wrote, "I was at a wedding with Louise a few weeks ago. I had heard certain rumours and asked her straight out, 'You're not thinking of going anywhere, are you?' 'Jaysus, no,' was the response.

"It is clear now that she lied to me. Who cares, no big deal. But the fact is that she more than likely had her mind made up well before the 5 June elections and that means that she also lied to party members and her constituents and I think that is a very big deal."

Carthy outlined that all Sinn Féin candidates sign a pre-election pledge which states that if a councillor leaves the fold they should give back their council seat to the party.

Minihan departed Sinn Féin three weeks ago and the reason she cited in a statement was "Sinn Féin has over the last 12 years moved steadily away from the core values of Irish socialist republicanism".

Carthy continued: "Louise texted me this morning. She said, 'Sorry I didn't get 2 speak 2 u b4 hand, always valued u as a comrade'. Comrades don't do this! Louise should do the honourable thing. She should give the seat back to the party."