The British Army tested a giant water pistol that can kill terrorists at close range during a recent NATO exercise in Belgium.

The NNTEX-16L exercise was hosted at the Elsenborn military camp where the British and Belgian troops were joined by colleagues from the Netherlands and the United States.

The watercannon -which looks similar to a Second World War-era flame thrower - has a backpack which can hold ten rounds of ammunition.

British troops tested a portable water cannon system which can kill at close range but will not cause collateral casualties at a special NATO training exercise held in Belgium this week

The device, which looks similar to a Second World War-era flame thrower, pictured here being carried by a US Marine on Iwo Jima, can be equipped to fire CS gas as well as water

At ranges less than three metres, the impact of the high-power water jet is likely to be fatal.

Between three and six metres, the jet will knock down an enemy.

According to details which have emerged from the NNTEX-16L exercise, the jet gun, which was developed in Germany, can be used in situations where firing live ammunition could lead to civilian casualties.

According to Defence Online, the exercise featured different types of less than lethal technology.

Danish, German, Norwegian and Austrian troops also took part in the operation, testing out some of the latest equipment.

Some of the devices on show included lasers, acoustic and kinetic devices.

Dr Jamie Shea, NATO Deputy Assistant Secretary General for Emergency Security Challenges said: 'Non-lethal capabilities are critical for force protection purposes and to give commanders a range of different options to bring potentially hostile situations rapidly under control, while avoiding escalation and the disproportionate use of force.'

Some of the devices tested used radio-frequencies to stop vehicles instead of requiring the use of conventional firearms.

Troops using such a system could stop a vehicle containing a potential suicide bomber, but which also could be driven by a civilian - without resorting to lethal force.