The Israeli health authorities say they have been unable to find the cause of the illness, which has struck widely scattered locations in the West Bank.

Dr. Baruch Modan, Director General of the Health Ministry, today repeated the finding of medical teams last week that no organic cause had been discovered. Teams from the International Committee of the Red Cross and the Centers for Disease Control in Atlanta are also due to start investigations.

At a news conference last week Dr. Modan said the original incident, affecting 32 girls in the village of Arrabe on March 21, might have been caused by ''some environmental irritant,'' which he did not identify. But outbreaks March 27 and 28 in the town of Jenin showed ''no organic basis,'' he said.

The symptoms were genuine, not faked, but they were ''subjective,'' he explained, related to what the patient feels rather than what can be objectively measured. Laboratory tests of blood and urine specimens from those admitted to hospitals showed nothing abnormal, he reported. Tests at the patients' schools turned up no chemicals; a yellow powder found on windowsills turned out to be a pollen quite common at this time of year. Mass Hysteria Theory

Dr. Modan suggested that some form of mass hysteria might have been involved. He read from a November 1966 issue of The British Medical Journal reporting identical symptoms that had affected large numbers of girls repeatedly in a school in London.