Vandervis said it was up to Cull whether the matter proceeded.
"Regrettably, defamation proceedings have had to be served, and once again it is up to Cull to take appropriate steps as he sees fit.''
The serving of legal papers was followed last night by Vandervis' decision to release a copy of his statement of claim to media.
The document confirmed Vandervis was seeking $250,000 in "general damages'' and another $250,000 in "exemplary damages'', plus costs.
The claim followed a heated exchange during a Dunedin City Council meeting last year, when Vandervis claimed to have paid a backhander to secure a council contract in the 1980s.
He was labelled "a liar'' by Cull and ejected from the meeting after suggesting he had given Cull "personal evidence'' to back his claim.
In May, both men claimed a report by internal auditor Crowe Horwath, examining the backhander claims, backed their positions.
Vandervis then threatened to "double the damages'' after Cull stood by calling him a liar in the wake of the report.
Cull would only say when contacted he would be focusing on his mayoral duties and making no further comment about the claim "at this stage''.
The Otago Daily Times understands the council had insurance to protect ratepayers from the cost of claims against elected representatives in their council duties, although it was not yet clear if a claim resulting from Cull's comments would be covered.
Ratepayers could still be left to pick up the bill for associated costs, including legal bills, should Cull lose, the ODT understands.
Cull was yet to file a statement of defence with High Court staff.
Idour said he had planned to serve the papers on Cull in the council's Civic Centre building, but had seen the mayor passing by while sitting in With Sugar Cafe.
"I was in there, having a coffee and talking, where I go most mornings, and he was walking rather fast down Stuart St. I saw him and shot out.
"I just took the time to explain what they were and handed them discreetly to him. He looked a wee bit shocked.''
Idour said he was acting as "process server'', under a barrister's instructions, and not working for Vandervis.
"I serve papers all the time.''