An investigation was held at an East Sussex fireworks factory that later caught fire and exploded, with the deaths of two firemen, MPs have heard.
Cameraman Brian Wembridge and sub-officer Geoff Wicker were killed
Communities and Local Government minister Angela Smith said the Festival fireworks site was visited by the Health and Safety Executive in October.
She told the Commons during a debate instigated by the local MP that a probe followed later that month.
But Ms Smith said there "was no specific evidence of wrongdoing".
She explained: "I won't go into all the details at present but a letter was passed to an explosives inspector responsible for the site."
The fire on 3 December claimed the lives of Geoff Wicker, 49, and support officer Brian Wembridge, 63.
Twelve other people were injured, including nine firefighters and a police officer.
The cause of the fire and explosion at Festival fireworks UK Ltd, on Marley Farm, The Broyle, Shortgate, is under investigation.
Sussex Police reopened The Broyle to traffic in both directions on Wednesday but said they were still conducting a major inquiry on the site.
The depot and nearby buildings were gutted in the fire
During Tuesday night's Commons debate, concerns about the procedures used in tackling the blaze at the factory were raised by the Liberal Democrat MP for Lewes, Norman Baker.
He also questioned whether explosive acetylene cylinders stored in a nearby plant were factored in to safety plans.
Mr Baker said questions needed to be asked about the licensing regime covering the site.
"There was a steel fabrication plant next door and that plant did contain as far as I can tell from reports so far acetylene gas cylinders.
"Obviously the idea of having those in close proximity to fireworks is not a very sensible one," he told MPs.
Ms Smith said licences had to take account of other hazardous materials, and a "separation distance" judged before one was issued.
She said the East Sussex Fire and Rescue Service had been "aware" of the proximity of the cylinders.
Mr Baker also asked if firefighters had been "sent in to a situation which they really shouldn't have been sent in to with the tragic consequences that we know?"
"We need a thorough inquiry, we need an open inquiry and we need to make sure lessons are learnt and this sort of tragedy never happens again."
Ms Smith promised a "full, thorough and transparent investigation".