Police were alerted to a potential terrorist plot after a London (search)-based group tried to buy half a ton of toxic chemicals from a biosciences company, a British newspaper reported Saturday.

The Financial Times said Amersham Biosciences (searchinformed authorities when it received an order for 1,100 lbs of saponin (search) -- a type of natural detergent derived from plants -- in the fall of 2002.

Saponin can be used to enhance the transmission of molecules through biological cell membranes, and the newspaper quoted experts as saying it could have been combined with a potent toxin such as ricin (search) and smeared in public places in a bid to cause mass poisoning.

London's Metropolitan Police would not comment on the report, and Amersham could not immediately be reached for comment.

The Financial Times said the order came from a firm with a London post office box address. The newspaper quoted Lennart Arlinger, Amersham's business development director, as saying staff became suspicious because of the large quantity ordered. Further research showed the group trying to buy the goods was funded by the "Islamic community," he said.

The company informed police in Britain and Sweden, where the order was handled, the newspaper said.

Saponins, which can be toxic in high doses, are a family of natural detergents with a variety of uses in industry and medicine. Digitalis, which is used to treat heart disease, is a saponin derived from the foxglove plant.

Early this year, several men were arrested and accused of plotting to produce a chemical weapon after police discovered traces of ricin -- a highly toxic poison extracted from castor beans -- in a north London apartment.