Seven north London have reaffirmed their support for a new waste incinerator in Edmonton after calls from Extinction Rebellion for the project to be paused over soaring costs.

A letter signed by Barnet, Camden, Enfield, Hackney, Haringey, Islington and Waltham Forest has been published stating that halting the North London Heat and Power Project (NLHPP) would undermine efforts to tackle the climate emergency.

The major piece of public infrastructure was given the go-ahead by the government three years ago, and would burn all of the rubbish from north London to generate electricity for 127,000 homes.

But in December campaigners opposing the site called for it to be halted after predicted costs spiralled from £650million in July to £1.2billion.

The project includes a community centre to promote the circular economy and a resource recovery facility to separate recycled waste.

Extinction Rebellion have proposed alternative ways for treating the non-recyclable waste produced by north London’s two million residents. The main suggestion is Mechanical Biological Treatment (MBT).

The North London Waste Authority (NLWA), which is behind the project, “considered and rejected” the suggestion, saying MBT is “unproven, unreliable, and beset with high-profile and costly failures across the UK”. It said it ultimately still created a fuel burnt in an energy recovery facility (ERF), adding: “It would simply be irresponsible to take such a reckless gamble with the delivery of essential services for north Londoners.”

The NLWA also said the coronavirus pandemic had highlighted how much people are failing to recycle and relying on their waste bins.

Councillor Clyde Loakes, chair of NLWA said: “We call on Extinction Rebellion to work with the NLWA and the boroughs in areas of common interest, such as the vital practical and campaigning work to reduce waste and increase recycling for the benefit of the planet and future generations. Supporting and encouraging our residents is an area where we could be working together to focus minds and secure much needed behaviour change”.

The NLWA says the NLHPP aligns with the boroughs’ mission to reduce waste and increase recycling, saying it will save the equivalent of 215,000 tonnes of carbon dioxide every year compared to landfill – which is like taking 110,000 cars off the road.

Hackney’s eco chief Cllr Jon Burke said the incinerator would eliminate the “uncontrolled cocktail of powerful greenhouse gases associated with landfill”.

He added: “By undertaking coordinated efforts to increase recycling and reduce waste; extracting valuable energy from non-recyclable material; and continuing to explore offsetting and capturing the carbon dioxide emissions generated by the plant, the NLWA is creating a model for the progressively decarbonised waste system we desperately require.”

Early pre-construction works have been temporarily paused due to the coronavirus crisis. Contractors bidding for the job were shown an online presentation during a virtual meeting this week.

Extinction Rebellion has been contacted for comment.