One of the UK’s richest boroughs has been accused of jeopardising people’s lives after it unilaterally vetoed a flagship scheme for safer walking and cycling under pressure from a tiny minority of residents.

Kensington and Chelsea council in west London pulled the plug on the programme before a formal consultation had been completed, after receiving about 450 emails opposing the scheme – less than 0.3% of the borough’s population.

A spokesman said councillors had also received “hundreds” of other emails and other solicitations from residents, saying the total could be up to 1,000 people, or 0.6% of the population.

The decision was announced on the eve of the second anniversary of the Grenfell Tower fire in the borough, in which 72 people were killed. Kensington and Chelsea has faced sustained condemnation over its stewardship of the block and its response to the disaster.

The scheme, which would introduce new pedestrian crossings and install protected bike routes along some of inner London’s more perilous roads, including Notting Hill Gate and Shepherd’s Bush, was being planned by the office of London’s mayor, Sadiq Khan, and Transport for London (TfL).

It would run on council roads though, meaning the authority had an effective veto. The council initially said it would take a neutral view before a consultation on the scheme, run by TfL, and then listen to the views of residents.

However, at a public meeting on Thursday evening attended by TfL officials, the council announced without warning it was opposing the plan, meaning it will not go ahead, without waiting for the results of the TfL consultation.

Will Norman, Khan’s commissioner for walking and cycling, said it was “a disgrace” for the borough to unilaterally veto a scheme on roads on which there had been 275 collisions in the last three years, with the vast majority of serious injuries being to pedestrians and cyclists.

“They originally supported consulting the public on the plans, and now midway have shamelessly decided to ditch their support, making a mockery of the idea of listening to the public,” Norman said.

“People will die and suffer serious injuries as a direct result of this cynical political stunt. The council’s stubborn opposition to making the borough safer for cyclists and pedestrians is putting residents at risk.”

Johnny Thalassites, the councillor who leads on transport and planning for Kensington and Chelsea, said the council was “surprised that TfL have taken such an aggressive tone”.

He said: “It is not a political stunt to listen to local residents and businesses, reflect their views, and ask for a rethink on their behalf.”

But when asked how many objections had been received, the council said it was about 450 emails, out of a population of 155,000, and “hundreds” of other messages. A council spokesman was unable to say how it was able to determine that the emails and other interactions reflected the overall opinion in the borough, or whether it attempted to do so.

Several of the objectors have been high-profile, including the TV presenter Jeremy Clarkson and actor Felicity Kendal.

The council has argued on the basis that vehicle journey times in one direction were modelled to be slightly slower with the cycle lane installed, and that this would cause slower traffic speeds and thus extra pollution.

Such claims are disputed and not seemingly backed by evidence. Readings at other London routes with protected bike lanes installed have shown significant falls in emissions.

Other objections included the loss or moving of two bus stops, and the removal of 23 trees for the scheme. TfL said two mature trees would be affected.

Kensington and Chelsea said it would submit its own plans for different cycle routes, which would not involve separated lanes and would send riders along back streets. There is no final timetable as to when this might potentially be built.

• This article was amended on 2 July 2019. An earlier version omitted the word “mature” from TfL’s description of the trees that would be affected.