A man who says he spent two decades collecting ecstasy pills of all colours and shapes as a hobby has turned to police for help after they were stolen - because he says some of them are poisonous.

Police say the 46-year-old man, who was not identified, decided to report the theft despite the illegal nature of the collection because he was worried about the possible consequences if anybody swallowed one of the poisoned pills.

It was not immediately clear why about 40 red-and-white pills out of the 2400-pill-strong collection would be poisoned, but the police say they fear the drugs could be lethal if swallowed.

"That's really the main reason he came to the police," police spokeswoman Esther Naber said on Thursday, adding the man "knows he's not going to get his collection back".

A report in daily on the same day said the man claimed he was not a drug dealer or user.