The pupil, the only girl among seven students aged between 16 and 17 on the trip, told her headteacher that Heather Lang had given her sanitary products away against her will to nuns in an orphanage, telling her, “They need them more than you do.”

Ms Lang, who taught at Bredon school in Gloucestershire, an independent boarding school which specialises in teaching pupils with learning difficulties, between 2001 and 2005, was not present at the hearing.

The committee, in Birmingham, heard that three days after the group returned from the trip, organised by World Challenge Expeditions, in August 2005, the school received a telephone call from the pupil’s mother, complaining about her treatment during the trip.

She said her daughter did not want to return to the school because she feared being mocked by fellow pupils following remarks made by Ms Lang.

The girl and two other pupils were subsequently interviewed.

Jonathon Bryant, the group leader from World Challenge, produced a statement, which said of Ms Lang: “She lost it and fell below the standards of professionalism.”

Another pupil on the trip said, in a telephone interview, that Ms Lang was “untactful with pupil A and said she stank”.

David Keyte, the headteacher, said he had no doubt that Ms Lang, who was 26 at the time of the trip and resided in the school, was adequately equipped and briefed to go on the expedition.

Cathy Moorhouse, who represented Ms Lang, said Ms Lang had not meant to upset the pupil but had not known how to tell her to take better care over her personal hygiene.

The GTC committee said that while Ms Lang’s behaviour amounted to unacceptable professional conduct, her behaviour had been out of character.

Ms Lang has since emigrated to Qatar.