New York City Mayor Michael Bloomberg says he's confident authorities are taking the right actions involving threatening letters addressed to him and his lobbying group that contain ricin.

(SOUNDBITE) (English) NEW YORK CITY MAYOR MICHAEL BLOOMBERG SAYING:

"Number one I have enormous confidence in the NYPD (New York Police Department) and the FBI and their procedures. We take a lot of security measures as you know. The men and women that open the mail for example, they are well-trained in procedures for something like this. This is not the first time we've had something like this happen to anybody."

Police said two anonymous letters, one addressed to Bloomberg, and one to his gun control group in Washington DC, tested positive for ricin.

Both contained threats against Bloomberg and mentioned the gun debate.

The discovery of the letters comes just weeks after ricin-tainted letters were mailed to President Barack Obama and other government officials