TEAR gas may not subdue violent boozed-up thugs, according to a new police training manual.

The manual offers guidance to officers on how to use the riot control agent.

Police carry CS spray to control and subdue rampaging drunks or violent thugs.

However, the paper - 'CS incapacitant spray - issue, use and storage' - says it may not work on people who suffer "serious mental disorders," or who have been drinking alcohol or taking drugs.

It also warns the spray would not work on dogs.

It even reminds officers not to spray "up-wind", as this could lead to spray back and injury.

According to the Police Scotland' manual: "CS spray will not work in all cases.

"Failures have been noted on three categories of subject:

"People with serious mental disorders, people under the influence of drink or drugs and people with positive mental mind set/goal."

The guide, obtained through a Freedom of Information request, added: "CS sprays do not affect animals in the same way as people.

"It is ineffective on dogs."

Chief Inspector Stuart Ord, from Police Scotland's Training team, said: "CS spray is an effective tool in helping our frontline officers keep the public and themselves safe.

"All officers who use CS spray receive an initial full practical training course during which they are required to show competence in its use.

"This initial training is reinforced through annual requalification training."

CS spray causes a burning sensation and forces uncontrollable shutting of the eyes.

However, it can also cause vomiting, disorientation, dizziness and restricted breathing.

CS spray is classed as a prohibited weapon under Section 5 (1) (b) of the Firearms Act, 1968, as such any discharge, loss or abuse of a spray will be scrutinised very closely.

rebecca.gray@eveningtimes.co.uk