The MBC TV programme late on Tuesday also interviewed some students who went on recent trips to China.

'Phone calls came to the rooms from the massage parlours which are everywhere in the hotels,' one student told MBC. He said about 30 of his schoolmates bought sex there.

The ministry ordered school officials to investigate all field trips to China. The TV programme said teachers were either helpless or negligent in their supervision.

AGENCE FRANCE-PRESSE