Somali officials and witnesses say a car bomb exploded killing two Ethiopian soldiers as the vehicle was driven into an Ethiopian military base in Somalia.
Wednesday's suicide bombing took place in the town of Baidoa near a hotel where Prime Minister Ali Mohamed Gedi was staying. The prime minister was unharmed.
An Islamist rebel group, Mujahidin Youth Movement claimed responsibility for the attack in an statement on its Web site. It denied that Mr. Gedi was the target, although there have been past attempts on his life.
Parliamentary members have been arriving in Baidoa to take part in a vote of confidence in Mr. Gedi's government.
The prime minister has survived two previous confidence votes with the support of President Abdullahi Yusuf. But recent reports suggest the president is no longer siding with Mr. Gedi.
Relations between the president and the prime minister deteriorated last month after Mr. Gedi dismissed a political ally of the president.
Lawmakers against Gedi also accuse him of doing too little to stop violence in Mogadishu.
At least seven people have been killed in the capital city since late Tuesday.
Witnesses in Mogadishu's southern Bulo Hubey neighborhood say gunmen with pistols shot three men in the area early Wednesday.
Gunbattles between Islamic insurgents and government forces have killed thousands of Somalis and prompted tens of thousands of Mogadishu residents to flee the city.
Some information for this report was provided by AFP and Reuters.