The Harvard and MIT communities felt the impact of the nation’s anthrax scare yesterday, as authorities confiscated suspicious pieces of mail at both institutions.

At Harvard, two separate letters caught the attention of the Harvard University Police Department (HUPD).

At 12:30 p.m., HUPD received the first notice of a suspicious letter at the Mallinkcrodt Laboratory. Thirty minutes later, another suspicious letter was reported at the Jefferson Laboratory.

In both cases, the senders of both letters were unknown to the letters’ recipients.

HUPD officers and staff from the University’s Environmental Health and Safety division responded to the reports.

In both cases an investigation determined that the letters were “suspicious enough to take away,” said HUPD spokesperson Steven G. Catalano.

However, neither letter was suspicious enough to warrant a call for help from the Cambridge Fire Department (CFD) Hazardous Material (HAZMAT) crews.

“We have nothing to believe that they were bio-safety hazards, but we’re being extra cautious these days,” Catalano said.

At MIT, a lecturer in the school’s foreign languages and literature department opened a piece of mail yesterday morning to find about a teaspoon of white powder.

The man contacted MIT Police, which, in turn, notified CFD HAZMAT.

The powder was taken to a state labotory for testing, and word of its composition is expected to be released today.

Soon thereafter, the MIT medical department took steps to decontaminate both the building and any individuals who were exposed to the powder.

A second report of white powder, at MIT’s Human Resources Department, proved to be a false alarm, according to a statement by David Diamond of the MIT Medical Department. The powder turned out to be dust from construction.

The scares yesterday led officials at both schools to reassure the educational communities.

Yesterday, University President Lawrence H. Summers posted a statement on the Harvard website in response to the heightened anxieties.

“Harvard remains in continuing contact with the appropriate public authorities, and we have no information to suggest that anyone within our community is at particular risk,” he wrote.

Anyone who is concerned with suspicious mail or any other security issues should contact HUPD at (617) 495-1212.

—Staff writer Alex B. Ginsberg can be reached at ginsberg@fas.harvard.edu.