The move follows incidents in which the probation officers have allegedly been strip searched on the premise that they might be bringing drugs and weapons into Britain's prisons.
Their resentment came to a head when they voted for the boycott at the annual meeting of the National Association of Probation Officers in Derby.
The new search procedures, including bra searches, have been brought in as part of a security clampdown in the wake of the Whitemoor and Parkhurst break-outs. But some probation officers believe that the rules, mainly aimed at prisoners' families and friends, are being exploited by prison officers to settle grudges.
Last night Roger Holmes, a London-based probation officer with 20 years' experience, said that he had walked out of Long Lartin jail in Worcestershire in disgust last month after prison officers demanded to look in his mouth.
Mr Holmes had already consented to searches of his hair and ears. He said: "I was told, 'Open your mouth and raise your tongue' and I said, 'Not bloody likely!' "
The Prison Officers' Association rejected the suggestion that unfair searching was taking place and said that officers were merely acting according to instructions from headquarters.Reuse content