Washington — After receiving a letter of protest from a U.S. congressman, the Department of Homeland Security abandoned its claim this week that eight foreign graduate students in oceanography who needed access to American ports for their research were security threats. However, the department did not reverse its decision to withhold security clearance from the students, who are enrolled at the Massachusetts Institute of Technology.

In May the department deemed at least two of the students as “security threats” when they applied for Transportation Worker Identification Cards, which are required for access to the secure areas of ports where research ships sometimes go. The two students are from Britain and Germany, and the Transportation Security Administration said they did not possess the necessary visas for clearance.

Rep. Brad Miller, a North Carolina Democrat who is chairman of the House Committee on Science and Technology’s Subcommittee on Investigations and Oversight, wrote a letter on June 6 to the department’s secretary, Michael Chertoff. Mr. Miller said the students had been unfairly labeled as security threats and were not suspected of terrorism or threatening national or transportation security.

Mr. Chertoff’s department responded by eliminating the “security threat” designation for the students, but saying that they may not obtain the identification cards simply because their visa-card category makes them ineligible for the cards. On Thursday, Mr. Miller wrote again to Mr. Chertoff, asking that the Transportation Security Administration lift the access restrictions against the foreign students. He noted that foreign maritime students are eligible for the identification cards and thus may gain access to secure areas. —Allie Grasgreen