The recruitment of black and Asian soldiers was held back for decades under a secret policy of "quotas" that ensured no Army unit became dominated by recruits from ethnic minority backgrounds.

The recruitment of black and Asian soldiers was held back for decades under a secret policy of "quotas" that ensured no Army unit became dominated by recruits from ethnic minority backgrounds.

Files released under the Freedom of Information Act today show that Army medical officers were instructed to make a note of all new recruits who did not have North European facial features.

Medical staff were told to secretly record details of "Asiatic or Negroid features" as part of a policy of "quota restrictions" which was regarded as so sensitive that not even ministers were told of its existence.

A briefing paper from November 1972, written for the Adjutant General of the Army and marked "Personal - in confidence", explained how the system worked.

"Officially, we state that we do not keep statistics of coloured soldiers," it noted. "In fact we do have a record, resulting from a description put on the attestation paper by the medical officer of the features of the recruit eg, north European, Mediterranean, Asiatic, African or Negroid, others etc."

Anyone identified as having non-north European facial features was designated "D factor", which was used to restrict the number of ethnic minority personnel serving in a unit.

The papers also show that medical officers were given considerable latitude in deciding which individuals should be classified as "D factor". It could be extended to someone of Mediterranean appearance or even a "swarthy Frenchman".

Files reveal that the policy began in the 1960s and was still being pursued in 1976.

The briefing paper said: "At the Manning and Record Offices a broad division is drawn between north European and all others and the punch cards for the latter are punched in such a way that they can be identified if required." It added: "The determination of the characteristics is at the discretion of the various medical officers and could include such examples as Chinamen, Maltese or even swarthy Frenchman."

The memo then went on to describe the purpose of the system, which at that stage had been going for 15 years.

"This system has been in operation since 1957 and enabled us to keep a check on the numbers of non-Europeans in the corps of the Army so as to ensure that our assimilation levels (quota restrictions) were being adhered to," it said.

A further note on the "D factor" from 1975 stated: "Between 1.5 per cent and 2 per cent of Army recruits have these characteristics. Since it stems from medical records, this information should not be disclosed outside the department."

A spokesman for the Ministry of Defence was unable to say exactly when the policy of quotas ended, only that "the Army is an equal opportunities employer."