The official's email said: "I need to advise you that there are strong grounds to believe that the Ethiopian government and the transitional federal government of Somalia and the African Union [peacekeeping] Force Commander, possibly also including the African Union Head of Mission and other African Union officials, have through commission or omission, violated the Rome Statute of the International Criminal Court.
"... there arise urgent questions of responsibility and potential complicity in the commission of war crimes by the European Commission and its partners."
"The situation is Somalia has gone from bad to worse after the intervention of Ethiopian troops"
Abed, Kumasi, Ghana
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Solomon Abebe, spokesman for the Ethiopian ministry of foreign affairs, called the allegations a "fabrication".
Abebe said: "The international community, everybody knows that this is false."
EU officials were not immediately available for comment because Friday was a public holiday in Kenya. Somali officials were unreachable.
European diplomats said they were concerned about the information.
Jens Orlander, the Swedish special envoy for Somalia based in Nairobi, said: "We are looking at this from a legal point of view at the ministry of foreign affairs in Stockholm."
Ethiopia expands 'Somali mission'
Ethiopia has reportedly sent more troops to Somalia to support a fragile African Union peacekeeping force in Mogadishu, the country's capital.
Local residents said they saw hundreds of Ethiopian soldiers in trucks moving to Mogadishu from the inland town of Baidoa on Friday.
"I have seen seven Ethiopian military vehicles coming from Baidoa. They were heading to the presidential palace," Abdul Kadir Muktar, a resident of southern Mogadishu, said.
A resident south of Lafole, south of the Mogadishu, Somalia's capital, said he saw at least four Ethiopian military vehicles heading to Mogadishu, also from the direction of Baidoa.
"There were some troops on board, but I do not know how many they were," he said.
The troops earlier flew into Baidoa, 250km northwest of Mogadishu, according to locals there, who reported seeing two large planes and at least nine military vehicles carrying dozens of soldiers.
Zemedkum Tekle, Ethiopian information ministry spokesperson, denied a new deployment and insisted Ethiopia had pulled out two-thirds of its forces from Somalia.