Image copyright Reuters

Advice urging the public to run and hide from gunmen was published by mistake on the government's website, the BBC understands.

A document advising "if you can't RUN, HIDE" was placed online by the National Counter Terrorism Security Office.

A source said the document - titled Developing Dynamic Lockdown Procedures - had been published in error.

It was due to put on the site next week during a security awareness week that was planned before the Paris attacks.

Sources stressed the advice was aimed at businesses and the security industry and was not a response to any specific threat.

It says: "Is there a safe route? RUN if not HIDE" and tells people to "find cover from gunfire".

The NCTSO is part of the National Police Chiefs' Council, and the mistake does not appear to have been made by government or Home Office officials.

The NCTSO has access to pages on the gov.uk website.