Police look at firing chemical irritants at rioters in search for 'less lethal' weapons, such as plastic bullets, to deal with civil disorder

Future riots could be quelled by projectiles containing chemical irritants fired by police using new weapons that are now in the final stages of development.

The Discriminating Irritant Projectile (Dip) has been under development by the Home Office's centre for applied science and technology (Cast) as a potential replacement for plastic bullets.

Documents obtained by the Guardian reveal that last summer's riots in England provided a major impetus to Home Office research into new-generation riot control technology, ranging from the Dip to even more curious weaponry described by Cast technicians as "skunk oil".

The briefing by Cast for the Police Service of Northern Ireland says that last year's disorder sparked a surge of ideas to the Home Office from the public as well as companies manufacturing police technology. To capitalise on the interest, Cast convened a "brainstorming" event in October. Participants included police from London and Northern Ireland, the Police Federation, the Serious Organised Crime Agency (Soca) and the Ministry of Defence's Defence Science and Technology Laboratory.

"No ideas too stupid or 'off the wall' to consider," the briefing notes record.

The November briefing, The Development of New Less Lethal Technologies, suggests that the Dips would be loaded into guns used to fire the existing generation of plastic bullets. They would be intended to be accurate at a range of up to 65 metres.

It is understood that the Dip, which was originally supposed to have been introduced in 2010, would be loaded with CS gas, pepper spray or another irritant.

Other parts of the briefing, released under the Freedom of Information Act, refer to a need in the short term by police to develop "counter laser dazzle" technology to protect officers from being dazzled by people using lasers like those used in recent Greek riots.

Large sections of the briefing were redacted by the Home Office, which designated them as "commercially sensitive". However, the Guardian understands that the "less lethal" technology discussed included heat rays and sound weapons. One weapon that particularly interested police officers was something Cast technicians referred to as "skunk oil".

The system would involve pellets containing foul-smelling liquids being fired from weapons similar to paintball guns. Such would be the smell that individuals hit by the pellets would want to go home to change their clothes, while associates would be reluctant to stay close to them.

The Guardian has also obtained figures illustrating the extent of recent spending by police forces around the country on the existing generation of plastic bullets, now referred to as attenuating energy projectiles (AEPs).

Some forces appear to have decided to considerably boost their stocks. Leicestershire constabulary spent £19,630 buying AEPs in 2010-11, doubling its spending on the previous year. So far in 2011-12 it has spent more than £10,000. Even a relatively small force, Avon and Somerset, which faced serious disorder in Bristol last year during the English riots and on a previous occasion amid anger over a controversial Tesco store, has spent more than £70,000 in the last three years. It also currently possesses 28 AEP launchers. That is 16 more than the larger West Midlands police, which still nevertheless spend more than £53,000 stocking up on AEPs in the last three years.

Gloucestershire police, whose territory was the scene of one of the more surprising outbreaks of rioting last summer, decided to considerably boost its AEP stocks last year. It spent £32,060 doing so, more than double its combined spending in 2009 and 2010. Elsewhere, Greater Manchester said it had sufficient supplies last year after spending more than £76,000 in the previous two years, while Nottinghamshire has spent £74,000 in the past three years.

A number of forces, including Merseyside and West Yorkshire, declined to provide information. Merseyside used the Home Office's claim that terrorism remains a "substantial" threat as a reason for not providing the information.

A final response has not been provided by the Metropolitan police. The Met commissioner, Bernard Hogan-Howe, told a meeting of the Metropolitan police authority last November that the force authorised the deployment of plastic bullets on at least 22 different dates last year.

Another freedom of information request from the Guardian found that the Home Office supplied £4.4m worth of AEPs between 2007 and March last year to police forces across England and Wales. The projectiles are supplied to the Home Office by the Ministry of Defence for police use.

While the Home Office invoiced forces for £700,000 worth in 2007-08, this rose to £1.2m in each of the following years and to £1.3m in 2010-11.