A House Democrat said Thursday that an envelope containing unidentified white powder was sent to one of his district offices - the latest incident attributed to hostile debate over the health care reform bill.

Rep. Anthony Weiner and a New York Police Department spokesperson said a hazardous materials team was examining the powder that arrived in an envelope at Weiner's office in Kew Gardens, New York.

A series of telephone threats, vandalism and other incidents have occurred in recent days as Congress debated and voted on the health care bill and an accompanying measure that made changes to it.

Also Thursday, the FBI joined in an investigation of threats to New York Democratic Rep. Louise Slaughter that included a brick thrown through a window at one of her district offices and a voicemail that she said referred to "well-trained snipers."