The Afar Revolutionary Democratic Unit Front (ARDUF) said in a statement it had apologised to the two Germans and handed them over to local elders.
Gunmen killed two Germans, two Hungarians and an Austrian in a dawn attack on a group of tourists in the remote Afar region on January 17, and seized two Germans and two Ethiopians.
The German Foreign Ministry said it could not confirm the release, adding it did not “want to comment further in the interest of those involved and in the interest of resolving the issue”.
The Ethiopian government quickly blamed its neighbour and arch-foe Eritrea for the deadly attack, saying it had trained and armed the gunmen.
ARDUF released a statement several days later saying it was holding the German tourists, but disputed the government’s version of events.
Hungarian survivors of the attack told how they were woken by gunshots in their campsite in the shadow of the Erta Ale volcano before being hauled from their tents and beaten with clubs.
University researcher Zoltan Winter told a news conference after returning to Hungary that the gunmen made them line up with other colleagues and fired shots at them.
Foreigners who venture out into the area usually include researchers, aid workers and about 500 adventure tourists each year, visiting geographical wonders such as the Danakil Depression, with ancient salt mines and volcanoes.
Afar is an arid stretch in Ethiopia’s northeast that is home to some of the world’s harshest landscape with high temperatures regularly exceeding 50 degrees Celsius in the summer.
In 2007, gunmen there seized five Europeans and eight Ethiopians. The Europeans were handed to the Eritrean authorities less than two weeks later and Britain said Asmara had helped to secure their release. The eight locals were freed a few weeks later.