WEST PALM BEACH, Fla. (AP) - Preliminary tests at two more post offices that handled mail for a Florida publisher have found a "minuscule" amount of anthrax, state health officials said Thursday.

The facilities in Boca Raton and Lake Worth will be cleaned and reopened Friday. The state health agency said no workers or visitors were believed to be at risk. More tests were planned.

A section of a third Boca Raton postal facility which handled mail for American Media was closed briefly this week after a small amount of anthrax was found in a sorting area. American Media is the supermarket tabloid publisher where a photo editor died of anthrax earlier this month and spores of the bacterium were found inside.

None of the more than 180 employees at the latest facilities are being tested for anthrax, Postal Service spokesman Joseph Breckenridge said.

Meanwhile, about 400 employees and free-lancers with American Media are awaiting results of a second round of blood tests to determine whether they were exposed to the disease. The results are expected Friday or Saturday.

The results also will confirm or rule out exposure in five employees whose initial tests last week showed the presence of anthrax antibodies in their blood.

Already infected is a 73-year-old mailroom worker, Ernesto Blanco, who remains in critical but stable condition at a Miami hospital, according to his stepdaughter Maria Orth. Another mailroom worker, Stephanie Dailey, tested positive for exposure but has not shown any symptoms.

The FBI has said it believes the anthrax that contaminated the American Media building in Boca Raton arrived in a letter because traces of the bacteria were found in the postal building that handled its mail. Investigators concede they may never find the mailing because it was probably thrown away.