Local authorities routinely have detailed emergency plans for natural disasters such as floods and man-made atrocities including terrorist attacks. But according to a "top secret" plan revealed after a freedom of information request, Bristol city council appears well prepared for a zombie attack.

A Mr P Store contacted the council wondering what plans have been laid down in case the undead invade. Rather than ignoring the request or dismissing it, an officer wrote back – light-heartedly, of course – setting out the best ways to tackle zombies and highlighting areas of the city considered high-risk areas.

Peter Holt, service director of communication and marketing, wrote back to Store: "In response to your request for details of Bristol city council's contingency plans for dealing with zombies, I can now release to you the following strategy document.

"Please note that this document contains various redactions as it has been considered that some information contained therein must be redacted for the purpose of safeguarding national security."

Marked top secret, the document, which has been published on the whatdotheyknow.com site, sets out four alert states:

• Ambient zombie level – business as usual, but be on the lookout for telltale signs.

• Enhanced activity level – confirmed zombie attacks on the populous.

• Major outbreak – zombie infection level in excess of 1%, multiple sightings across the city.

• Zombie pandemic level – concentrated outbreak, with infection levels over 30%.

The report suggests certain parts of the city – Whitchurch Park, Shirehampton, and Totterdown – are particularly at risk and adds that "false positives have been found in Stokes Croft", the city's bohemian quarter that was the scene of riots this year after the opening of a new Tesco store.

To avoid "widespread panic" staff are asked to listen for codewords on radio and television broadcasts to warn them that a zombie attack is under way.

Under health and safety the document urges staff to remember the correct zombie-killing procedure: "Fully disconnect the brain-stem from the body through either blunt force or full head removal."

In the procurement section the document claims "cuffs, stun guns, protection suits etc" are available on the staff intranet.

An annual training schedule for designated officers is in place, the document reveals. "To avoid public panic, this is billed as a gaming festival," the report says and adds that staff "fully qualified in zombie handling may qualify for partial exemption and accreditation in the training for handling pirate outbreaks and for spotting the difference between genuine hot air balloons and evil, giant, floaty space aliens."