Two little known Eritrean rebel groups said on Friday they had killed 12 government soldiers in an early morning attack.

The Red Sea Afar Democratic Organisation (RSADO) and the Eritrean National Salvation Front said they carried out the raid on Thursday in Kermed, Adi Metras, Ingra Abo, Adi Tela'a and Meshal Akran, all in southern Eritrea.

The enemy units were engaged for nearly two hours, the groups claimed in a statement.

They suffered both human casualties and material losses that included 12 dead and more than 15 wounded, in addition to various types of military hardware.

The claims were the first since last year when RSADO said it killed 17 intelligence agents and wounded another 37 in an attack on army barracks.

There was no immediate comment from the Eritrean government but authorities in Asmara often dismiss foreign-based opponents as puppets acting under the orders of foreign governments.

Eritrea accuses arch-foe Ethiopia of working to destabilise the Red Sea state, while Addis Ababa declared openly in April that it would support Eritrean rebels in a bid to oust President Isaias Afewerki's administration.

RSADO says its operations are in response to Asmara's refusal to grant autonomy to the Afar, whose homeland straddles Eritrea, Ethiopia and Djibouti.