A letter by a "heart-broken" wife led to the arrests of 35 Thai women working illegally in an entertainment outlet in Perak, a report said today.

The disgruntled wife sent a letter to the state Immigration Department complaining of "all sorts of problems" following the presence of the ladies in town, said department director Ishak Mohamad.

"An operation... was launched right after we received the letter from a lady explaining all the problems that arose following the arrival of the illegal workers at the entertainment outlets," he was quoted by Bernama news agency as saying.

The letter, signed by "a heart-broken wife", had resulted in a haul of two other Thai nationals and three locals, he said.

The foreigners, who did not have valid travel documents, had breached conditions of social visit passes and overstayed their visas, were held for questioning and further action.