European Union diplomats say they are investigating whether Ethiopian and Somali government forces have committed war crimes in Somalia.
The investigation was apparently triggered by an e-mail sent to Eric van der Linden, the EU ambassador to Kenya.
The message said there are "strong grounds" to believe that Ethiopian and Somali troops have intentionally attacked civilian areas. The writer also suggested possible involvement by African Union peacekeepers from Uganda.
Reports from the Associated Press and New York Times say the e-mail's author is a senior security adviser. EU officials have declined to reveal the person's name but confirmed the message's authenticity.
Nearly 400 people were killed in the Somali capital, Mogadishu, last week as Ethiopian and Somali government forces battled insurgents.
The New York Times quotes Ethiopian and Somali government officials as denying their forces attacked civilians.
The violence has disrupted Somali government plans for a national reconciliation conference. The conference was scheduled to begin in Mogadishu April 16, but officials including Prime Minister Ali Mohamed Gedi say the conference may be postponed.
Somalia has been plagued with almost continuous chaos and violence since 1991, when warlords overthrew dictator Mohamed Siad Barre.