A major fire at the Berkshire base where the UK's nuclear missiles are assembled was contained only after local fire crews requested back-up from emergency services outside the county, according to record logs of the incident.

The logs, obtained by the Observer under the Freedom of Information Act, reveal that the scale of the blaze was far bigger than has previously been acknowledged and have raised new concerns about safety at the Atomic Weapons Establishment (AWE) Aldermaston base in Berkshire.

They show that the Royal Berkshire Fire and Rescue Service (RBFRS) was forced to request a high-volume pump from London as it battled to contain the blaze in a protected building housing high explosives.

The release of the logs comes as the local council is expected to give planning approval this week for Project Hydrus, the next generation of thermonuclear warheads that will cost hundreds of millions of pounds to develop.

The logs establish that 20 appliances and 95 crew fought the fire for almost nine hours. At one stage, three miles of hose were in use as crews attempted to bring the fire at the base, which employs some 4,300 people, under control.

According to the logs, when the fire broke out shortly after nine in the evening on 3 August this year AWE initially informed the local fire service that it did not request its help in tackling the blaze. At 10.50pm RBFRS fire crews radioed their base to request a high-volume pump, a sign the blaze was considered a major fire. But requests to borrow a pump from several fire services in neighbouring counties were unsuccessful, and it was only at a quarter past midnight that a pump was located more than 40 miles away in London.

When support arrived from the Hampshire fire service, its appliance was temporarily prevented from entering the site by security officials. A fire service Land Rover also encountered a similar problem.

Firefighters initially used "Delta Defensive" mode, indicating that they believed the risk could not be controlled by the crews in attendance. By 4am, some seven hours after the blaze started, the record logs reveal that RBFRS told neighbouring fire services in "Hants, Oxon, Bucks, Surrey and Wilts that we are unable to provide any mutual aid at present due to this incident".

In fact, so many appliances were needed at AWE that the service had only one pump available to tackle any subsequent fires across the whole of Reading.

Peter Burt, director of the independent Nuclear Information Service, said: "The fire on 3 August was handled in a very questionable way by a company [AWE] which boasts that public safety is its top priority."

In response to questions asked this month by Green party MP Caroline Lucas, the Ministry of Defence revealed that since 2006 there have been four incidents at AWE Aldermaston where the Royal Berkshire Fire and Rescue Service has been requested to attend. The RBFRS was also requested to act as a stand-by on a further three events.

West Berkshire Council has confirmed that its Eastern Area Planning Committee will consider the planning application for Project Hydrus at a meeting on Wednesday. As has been the case with previous planning applications for AWE sites, council officers are recommending that the committee grant permission for the development to go ahead.

A spokeswoman for AWE said it took "extremely prompt action" to deal with the fire. "Within two minutes of being notified of the fire, AWE's Fire and Rescue Service notified Royal Berkshire Fire and Rescue Service and put them on standby before calling them to attend 15 minutes later. "On arrival RBFRS took the primary operational role after being fully briefed on the situation, including the involvement of explosives."

AWE said it had launched an investigation into the causes of the fire and its findings "will be shared with the public". A separate investigation is being carried out by the Health and Safety Executive.