He said 20 percent were locked up for various crimes involving theft and crimes they had committed under the influence of drugs.

Al-Qahtani warned against a systematic invasion of the Kingdom by drug traffickers targeting all sections of society.

He said the number of female inmates was still low. "Women represent about 2 percent of inmates in all prisons," he added.

Al-Qahtani, who was talking after a workshop in Riyadh on Sunday to define the needs of those working to tackle drugs, said more and more women were now using them.

He asked researchers of the Saudi Center for Anti-Drugs Studies and Research to visit prisoners in order to conduct detailed studies on means of tackling such offenses.

Meanwhile, the Directorate General of Drugs revealed that 67 million narcotic pills were confiscated last year. It said there were secret factories manufacturing these pills, which were capable of causing mental breakdowns within three months.