Wanganui Mayor Michael Laws has ordered his council to tear down signs erected this morning by the New Zealand Land Transport Agency (NZLTA) that advise travellers they are approaching "Whanganui".

Mr Laws led protests against the inclusion of an "h" in Wanganui and had the support a majority of local people.

Land Information Minister Maurice Williamson announced in December the official geographic name for the city of Wanganui could be either 'Whanganui' or 'Wanganui' and Crown agencies, such as NZLTA, were expected to change signs only when they needed replacing.

Mr Laws said his office had been inundated with complaints this morning after the large signs were erected.

"This has been a deliberate and provocative act by NZ Land Transport and undertaken with not the slightest discussion with ourselves.

"I have confirmed with the Minister of Land Information's office this afternoon that the official name of Wanganui is still 'Wanganui'. That the legislative law change required to gazette any new variant has not been passed by Parliament.

"Even when it is passed, Wanganui will still have two formally gazetted names - Wanganui and Whanganui - and Land Transport needs to officially recognise that in its signage. We would have dual names and both are equally valid.

"NZ Land Transport has illegally rebranded our city. Hence the removal of their signs."

NZLTA said it would issue a response shortly.