Wanganui District Council got an "h" added to its name this week in an act Mayor Michael Laws describes as petty vandalism.
Someone removed the bronze W from two signs on the council's office buildings on Tuesday night and replaced it with a plastic "Wh". A formal complaint has been laid with the police.
Last week, the council met to frame an official reply to the NZ Geographic Board after it was asked to consider the issue of the proper spelling of the city and district following iwi group Te Runanga o Tupoho's application for a change to Whanganui.
The council voted to advise the board, on behalf of the wider Wanganui community, that no change be made to the spelling of "Wanganui, either city or district".
Local iwi had been campaigning for the name change, saying Wanganui was misspelled and it was the right of Maori to assert the correct spelling of their language.
Since then, there has been an attack on Mr Laws' home in which someone threw a rock at his daughter's bedroom.
Mr Laws called that attack a "cowardly retaliation for my stance on the Wanganui spelling issue".
He offered $500 for information leading to the conviction of the person responsible, and listeners to his Radio Live show and Wanganui residents have boosted that to $2100.
Mr Laws said yesterday that Tuesday night's "petty vandalism attack" on the council office buildings, coming after the rock attack on his home, was "only hardening the Wanganui community's resolve to resist the 'h' cause".
"There is a growing community backlash against activists seeking to ram their minority cause down the public's throat," he said.
"The key point is that it won't make a blind bit of difference to the resolve of the council or the community to keep the spelling of Wanganui, and our city's integrity, intact."
Local Maori leaders said last week's council vote against putting an "h" in Wanganui would not be the end of the matter.
They said the proposed change was not a debate between Maori and Pakeha, but rather righting a wrong.