Two Somalis died when a bomb they were making detonated in a house in the Ethiopian capital Addis Ababa, as thousands gathered to watch a football match, officials have said.
"The ones who died were of Somali origin," Ethiopia's Minister of Information, Redwan Hussein, said on Monday.
The two deceased were in Ethiopia illegally and had rented a house in a Somali neighbourhood near the airport where the bomb exploded, Redwan said.
"They were Somali nationals and plotted to carry out a suicide attack disguised as fans on either the stadium or areas where large crowds gathered to watch the game," government spokesman Shimeles Kemal said.
Explosives, arms, hand grenades and football shirts were found at the scene of the blast, at a residential address an hour before kick-off, Shimeles said.
"Heavy police presence must have caused their nervousness and state of agitation which led to the detonation that caused their own death," Shimeles said.
Three suspects were detained.
Neighbouring Kenya has been a frequent target of attacks by the al-Shabab armed group, that has demanded Kenyan troops leave Somalia.
'No plans to withdraw'
Last month, at least 67 people were killed during a four-day siege carried out by some of its fighters who ambushed an upmarket shopping mall in Nairobi.
Ethiopia, which shares a long border with Somalia, sent troops into the country in 2011 to help African Union and Somali forces fight al-Shabab.
Redwan said several "terrorism plots" had been foiled on Ethiopian soil in the past, including a plan to target an African Union summit in 2010, and added that security in the country remains tight.
AU forces have been in Somalia fighting the al-Shabab since 2007 and have pushed them out of all major towns, including the capital Mogadishu and the key port town of Kismayo. But the group still controls swathes of rural areas in the south.
Some Ethiopian troops started pulling out of Somali this year, but following the attacks in Nairobi, the Addis Ababa government said it had no plans to withdraw its forces from Somalia.