Health and safety investigators are to inspect an atomic weapons base after fire broke out inside a bunker.
The fire started at the Atomic Weapons Establishment (AWE) in Aldermaston, Berkshire, on Tuesday.
A worker was injured and people living close to the site, which maintains warheads for the UK's nuclear deterrent, Trident, were evacuated.
The Health and Safety Executive said it had started a preliminary investigation with its internal teams into the cause.
A 600m (650yd) cordon was put up around the site following the fire, which broke out within a non-nuclear explosives area, on Tuesday night.
A spokesman for the Health and Safety Executive (HSE) said a team from its hazardous installations directorate was taking the lead.
Inspectors will carry out assessments in the concrete bunker on the site where the fire started.
AWE said there were no radiological implications as a result of the incident.
An independent investigation into the cause of the fire has been commissioned by AWE, and all findings will be made available to its independent regulators, the Nuclear Installations Inspectorate.
The findings will be made public during briefings with the AWE Local Liaison Committee which is made up of representatives of local authorities in Hampshire and Berkshire.
Richard Benyon, MP for Newbury, whose constituency includes the town of Aldermaston, supported the inquiry and said people had the "right" to be concerned.
"We want to get to the bottom of it," he added.
"We look forward to the report from the Nuclear Installations Inspectorate and I will be involved in it throughout."
Caroline Lucas MP, Green Party leader, said she had written to the Ministry of Defence following the fire and called for an independent inquiry into the cause.
She also asked whether the AWE off-site contingency arrangements, aimed at protecting the public from a radiation emergency, were put into operation.
"I also request that operations of the type that led to the fire are halted until the results of the inquiry have been published," she added.
The AWE provides and maintains the warheads for the submarine-launched nuclear deterrent.