The New Zealand Transport Agency was prepared to call in police to stop Wellington's rainbow crossing being painted. (File photo)

Police were almost called in to prevent Wellington's rainbow pedestrian crossing from being painted because of safety concerns.

The crossing at the intersection of Cuba and Dixon streets was painted in October after being signed off by Wellington City Council in an effort to be more LGBTQI-friendly.

But documents released under the Official Information Act show the New Zealand Transport Agency had concerns about pedestrian safety, and were prepared to call in the police to stop the project going ahead at one point.

In a draft letter to the council, which was never sent, the agency said it would call police to intervene if the project was signed off.

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MONIQUE FORD/STUFF The agency said the crossing's unfamiliar design, combined with the volume of traffic, posed a significant risk to pedestrians. (File photo)

"Should the council proceed to install the markings, the agency will direct their removal, ask the police to prevent their installation and/or remove the markings, and proceed to prosecution."

The agency's concerns over the crossing were that its unusual colours could cause confusion between drivers and pedestrians about who had right-of-way.

The central city intersection was a busy one, frequented by people of all ages, and there had been two pedestrians injured there in the past five years, it said.

Because of the unfamiliar design and the volume of foot traffic, there was a "high risk of confusion and a dazzling and distracting effect".

Police agreed with the council, but were in favour of a more measured approach.

MONIQUE FORD/STUFF The crossing was opened in October last year at the intersection of Cuba St and Dixon St, but not before Wellington City Council agreed to some design changes. (File photo)

"Whilst police support celebrations of diversity, our view is that this proposal poses risks of death and serious injury for road users," it wrote to the council.

"While acknowledging the police power pursuant to the [Land Transport] Rule ... our preference would be a negotiated resolution to this situation between the parties."

Days before the crossing was due to be painted, the agency asked for a final design and safety assessment to be supplied so it could grant an exemption.

According to emails, the report was received after the crossing was painted, and before an exemption had been granted.

The council's safety report concluded there would be "little residual safety concerns".

It noted changes it had proposed to make the crossing more safe, including speed cushions, thickened white lines, and a smaller painted area.