A group of about 200 Eritrean soldiers have besieged the ministry of information in the capital, Asmara, and forced state media to read a statement on air demanding the release of political prisoners.
The small nation, which gained independence from neighbouring Ethiopia in 1993, is a one-party state ruled by president Isaias Afewerki.
There was no immediate indication that the latest action was a coup attempt.
An Eritrean intelligence official told Reuters that the soldiers forced the director of state television to make an announcement.
"The soldiers have forced him to speak on state TV, to say the Eritrean government should release all political prisoners," the unnamed source said.
The daughter of Afewerki is among ministry officials currently being besieged by the soldiers.
Eritrea restricts access to foreign reports and is considered one of Africa's most opaque countries. Human rights activists have slammed the government for its repressive and closed policies. The website of the ruling People's Front for Democracy and Justice (PFDJ) party is inaccessible.
A statement has reportedly been read out on state radio and television calling for the implementation of the country's 1997 constitution.
One opposition activist in exile in Ethiopia told Reuters that there was growing dissent surrounding the Eritrean military.
"Economic issues have worsened and have worsened relations between the government and soldiers in the past few weeks and months," one activist told Reuters.
United Nations' Security Council has imposed an embargo on the Red Sea state over concerns it was financing and arming the al-Shaabab rebels in Somalia.
Gold companies with mines or projects in Eritrea include Sunridge Gold Corp, Nevsun Resources Ltd and Chalice Gold.