Anthrax scare hits US police stations

Last autumn's anthrax attacks in the US killed five

Authorities say at least 11 police stations in the US state of Massachusetts have received threatening letters containing white powder, raising fears of an anthrax attack.

However initial tests ruled out anthrax, officials said.

"It appears to be a hoax," state health department spokeswoman Roseanne Pawelec was quoted as saying by Reuters news agency.

She said the Federal Bureau of Investigation was investigating the source of suspicious envelopes mailed to police stations north of Boston.

Hamilton police chief Walter Cullen said that the letter opened in his department contained "a white piece of paper that said 'Black September' and then powder spilled out onto my secretary's desk."

Investigators are still searching for clues to last year's attacks

Five people died in the US last autumn after coming into contact with a series of letters containing anthrax spores in the mail. Those crimes have not been solved.

Besides Hamilton, police departments in the towns of Middleton, Danvers, Marblehead, Salem, Peabody, Wenham, Lynnfield, Topsfield, Lynn and Saugus received similar letters.

Hazardous materials crews were called in, and the incident was expected to raise fears of new terror attacks as the anniversary of the 11 September hijackings approaches.

"We have a nit-wit out there who is doing this... Whether it is something that is poisonous or whether it is nothing more than baby powder, we have to take it very, very seriously," Chief Cullen told Reuters news agency.