Sermkiart said he had worked in construction and as a charcoal-seller after quitting a teaching job. "I also sold underground lottery tickets and even served a prison term," he said, without divulging his crime.

"I don't want my daughters to face hardships like I did; so I want to take part in selecting the right men for them. I am only seeking a wider rage of options for my daughters."  Sermkiart, 56, made headlines when he erected a sign in front of his apartment in Buri Ram's Muang district announcing he was looking for sons-in-law.

Qualified applicants - healthy males between 25 and 35 with high school diplomas and a good moral character -must undergo a three-year unpaid businesses apprenticeship before being approved.

"I, contrary to what many people have said, am not crazy. I am like any father who wants his daughters to marry good, responsible men. But I am too busy with my businesses to help them select good candidates for themselves, so I put up the advertisement," he said.

Sermkiart has since set a new condition - the candidates might be asked to briefly stay in confinement to familiarise themselves with the kind of adversity he once endured.

His daughters would be free to accept or reject the applicants, Sermkiart said. The businessman said he would, however, not want excessively smart candidates, or those richer than himself.

"Smart people are difficult to control . . . those who want to enjoy my wealth but are unwilling to undergo the hard tests won't be selected.

"I will carry on until I find the right candidates," he said.