The manufacturer of the Ajax family of armoured vehicles for the British Army has admitted noise and vibrations have been "a feature of the design since 2010".
The Government has previously stated "anecdotal reports of vibration" were made after soldiers took part in pre-trials training on prototype variants of the Ajax vehicles in 2019.
General Dynamics is working to a contract worth up to £5.5bn to provide the UK military with the vehicles.
All trials involving Ajax were suspended again last month when it also emerged that some crew members involved in the trials were continuing to receive medical attention after concerns were raised over "noise and vibration levels".
Tests of the programme were previously "paused as a precautionary measure" between November 2020 and March 2021.
Representatives from General Dynamics appeared at a Defence Select Committee hearing to speak about Ajax.
Carew Wilks, Vice President and General Manager, General Dynamics Land Systems-UK, said: "If we're talking about noise and vibration on the platform, this has been a feature of the design since 2010 when we started work on the programme.
"Armoured vehicles such as this require a balanced design to meet all the requirements, and with the engine configuration and other characteristics, there is noise and vibration on the platform."
Watch: Trials involving Ajax were suspended again last month.
Scott Milne, Executive Programme Director, General Dynamics Land Systems-UK, added: "From the inception of the contract, the control of noise and vibration is a key feature of the design.
"We put design features in from the very start of the design to make sure the noise and vibration generated to the platform does not exceed legislation limits and action values.
"Throughout the development phase of the programme, through the seven prototypes and for each production variant, we have tested the noise and vibration levels of the platform – those levels are comparable to other armoured fighting vehicles within the [General Dynamics] family and in service today," he said.
Later in the Defence Select Committee hearing, defence minister Jeremy Quin said he would be "very surprised" if initial operating capability (IOC) was declared in September 2021.
He told the House of Commons in June this year that there was "90% confidence" of IOC meeting the September target.
Mr Quin then told the hearing there are "serious issues with noise and vibration" which must be resolved before IOC is declared and that he hopes trials of the Ajax vehicles will resume soon.