Updated

Greek authorities say they are investigating a death threat Foreign Minister Nikos Kotzias received that mentioned Greece's negotiations with neighboring Macedonia over its name.

Minister of Public Order Nikos Toskas said Friday that Kotzias was sent a letter that "contains threats to him and his family." Toskas says other government ministries also got threatening letters, but he didn't elaborate.

Greece is in talks with Macedonia for the republic to modify its name, which is perceived as a territorial threat to a Greek region also named Macedonia.

The effort to end a 25-year impasse has angered many Greeks, who say Macedonia is an integral part of Greece's ancient heritage and the government should take a tougher line.

A mass demonstration against the proposed compromise is planned in Athens on Sunday.