The leaders of Ethiopia, Sudan and Yemen have criticised neighbouring Eritrea, saying it is working to destabilise the entire region.
Eritrea fought a bitter border war with Ethiopia
Sudan's President Omar al-Bashir accused Eritrea of arming and training rebels in the western Darfur state.
Ethiopia's leader denied that the three countries were forming an anti-Eritrea alliance but warned that each state could "face Eritrea individually".
The three leaders are also discussing ways of fighting the al-Qaeda network.
Ethiopia's Prime Minister Meles Zenawai is hosting Mr Bashir and Yemen President Ali Abdullah Saleh in Addis Ababa after the three countries signed a pact in October.
Relations between Ethiopia and Eritrea are tense after Mr Zenawi refused to accept an international ruling demarcating their border, which caused a two-and-a-half year border war, ending in December 2000.
Eritrea and Yemen have clashed over the Hanish archipelago in the Red Sea.
"It is a fact that Eritrea has problems with all its neighbours," Mr Meles said.
"Eritrea has problems with neighbouring countries, and the only way out is for it to have dialogue and not confrontation," Mr Saleh said.
The BBC's East Africa correspondent Christian Fraser says that outside the regional disputes, there are still hopes that these three countries will take this opportunity to further coordinate their efforts to hunt down suspected al-Qaeda activists.
The US military say this new collaboration between the leaders of Sudan, Yemen and Ethiopia has helped improve security in the region.