Minister for Defence Procurement Jeremy Quin outlined the total spend on the project for the past 10 years after a written question from shadow defence minister, Labour MP Stephen Morgan, who asked for a breakdown of the financial commitment to date.
Trials of the Armoured Reconnaissance Vehicles were "paused as a precautionary measure" between November 2020 and March 2021 after personnel needed medical attention following concerns raised by crew members over noise and vibrations.
On 8 June, Mr Quin said some crew members involved in the trials are continuing to receive medical attention.
The cost so far
In terms of the demonstration phase of the Ajax programme, the Government has made payments totalling £688.64m, spending the most individually in 2014/15 (£155.37m).
After the manufacturing phase began in 2014/15, the MOD spent £2.29bn, spending a high of £564.51m in 2019/20.
The breakdown provided by Mr Quin also said that additionally £188m had been spent on in-service payments outside of the demonstration and manufacture phase costs.
The defence minister told the House of Commons earlier this month that the agreement with General Dynamics for Ajax is a "firm price contract", with £5.5bn "the maximum that is payable, including VAT".
What is the Ajax?
The Ajax family of vehicles - of which there are seven variants - are being designed to be the British Army's 'eyes and ears' of the battlefield.
Watch: Is the Ajax programme 'doomed to fail'?
Defence Secretary Ben Wallace said Third Division would "remain the heart" of the UK's warfighting capability, and would be built around a "modern armoured nucleus" – including Ajax.
To date, 14 Ajax vehicles have been delivered to the MOD, including the Ares variant, which is designed for reconnaissance and troop-carrying.
The MOD has said training on the Ajax variants has since recommenced following the pause.
Plans remain for the vehicles to be given initial operating capability in the coming months.
Ajax will be a fully digitised, tracked, medium-weight core of the British Army's deployable intelligence, surveillance, target acquisition and recognition (ISTAR) capability.
Cover image: Ajax vehicle pictured during a demonstration at Salisbury Plain Training Area (Picture: MOD).