Controversial Auburn councillor Hicham Zraika has been sensationally expelled from the Labor party after his failure to vote for his ALP colleague saw embattled deputy mayor Salim Mehajer re-elected to the position.

In a decision that will send shockwaves through the NSW ALP and pose potential problems for opposition leader Luke Foley in his seat of Auburn, the Internal Appeals Tribunal expelled Cr Zraika for unworthy and disloyal conduct.

It was Cr Zraika's second run-in with the party's internal tribunals, having been suspended from the ALP for six months in January by the higher Review Tribunal for branch-stacking offences.

However, on Wednesday night Labor sources insisted it was highly likely the expulsion would be overturned on appeal.