Frankfurt - A man who tried to blackmail a German unit of Swiss food giant Nestle by lacing some of its products with poison was sent to jail on Thursday after his hand-over ploy - homing-pigeons - led to his capture.

Alexandru Nemeth, 43, a Romanian-born German metal worker, admitted that he had demanded DM 25 million (R80 million) worth of diamonds, which were to be placed in small pouches hung around the necks of pigeons trained to find their way home.

The police eventually got Nemeth after two years of investigation when a pigeon called "Charly" led them to his allotment.

Nemeth, whose hobby was breeding homing pigeons, said he thought he had found a perfect way to blackmail but had since realised his mistake.

A Frankfurt regional court found him guilty of three counts of extortion and six counts of poisoning food products provided to supermarkets by Thomy, a unit of Nestle. It sentenced him to 11 years in jail.