ARMY chiefs have drafted in tough rules to stamp out illegal drug use in the ranks for good.

For the first time, any soldier who fails a drugs test will be booted out immediately — and banned from rejoining, or enlisting with the reserves.

Even those who unwittingly or accidentally take banned substances are not safe.

The new rules state that anyone who can prove they did not wilfully take drugs can only stay in if cleared to do so by the Chief of the General Staff, the head of the Army.

Sources said the diktat had come from Defence Secretary Gavin Williamson, who has demanded a tougher stance from top brass after damaging headlines.

Under the old policy, commanders had the discretion to let soldiers remain after a failed drugs test if they showed promise or were still in training.

Insiders hailed this a second-chance option to help those particularly from vulnerable backgrounds, where drug use might be rife.

Squaddies kicked out over drugs could also rejoin after two years, if they consented to strict rules like regular testing.

Both loopholes were closed under the zero tolerance policy, sent to commanders on Wednesday.

A defence source, said: “This is good for the Army. The grey areas are gone. Now if you do drugs you’re out, no ifs, no buts. If you fail a test you can never come back.”

Last month The Sun revealed Guardsman Lall, the first Sikh from the Coldstream Guards to wear a turban at Trooping the Colour, had failed a drugs test for cocaine.

The Army has also taken flak for failing to rule drug-shame soldiers ineligible for rejoining bonuses.

A Force spokesman said: “The Army does not tolerate drug abuse within its ranks. Soldiers caught taking drugs will be discharged.”