The instructions contain a strange mixture of seemingly ludicrous and out-dated attitudes towards gay people - passive partners might be spotted by their feminine gestures, clothes and make-up, they suggest - coupled with the threat of dismissal if services personnel refuse to submit to intrusive and possibly painful medical examinations.
The Royal Navy documents were obtained by Stonewall, the gay rights group. Yesterday Angela Mason, executive director, said they were a 'a blueprint for witchhunts against lesbians and gay men'.
Labour MPs are expected to raise questions about them on Monday, when the armed forces disciplinary procedures are due for annual review.
Although the ministry recently decided no longer to pursue criminal charges against gay and lesbian servicemen and women, homosexuality in the forces remains a technical offence. In the three years up to 1991, 272 homosexual men and women were discharged and a further 34 court- martialled and imprisoned for up to two years. In banning gay servicemen and women, Britain is out of step with several of its allies. Forces in France, Spain, Denmark, Belgium, the Netherlands and Norway are open to gays and lesbians.
The documents imply gay men are effeminate and predatory misfits who frequent bars and indulge in 'unnatural' acts. It carries the warning that homosexuals are 'often the source of sexually transmitted diseases' but says 'a homosexual act of itself is not life threatening'.
Although the documents were drawn up in 1987, Stonewall says they remain in force. Yesterday a ministry spokesman said he could not discuss any confidential documents. 'Our policy always has been that we discharge homosexuals because homosexuality is not conducive to a military atmosphere,' he said.