The rebel Oromo Liberation Front (OLF) on Sunday denied any involvement in Friday's bomb attacks across Ethiopia's capital Addis Ababa.
"We are not related to these bombings in any way," OLF spokesperson Lencho Bati said in a statement.
"The OLF is not involved in these attacks," he added.
On Friday, a series of unclaimed explosions hit different parts of the capital, killing four people and injuring 42 others. The attacks came days before the anniversary of last year's general election on Monday.
No one has claimed responsibility. But police suspected the OLF for such acts.
The OLF evolved from a political party into an armed movement nine years ago, claiming that the rights of the Oromo people, who make up almost 40 percent of Ethiopia's 70 million, were not being respected.
The OLF are now fighting Prime Minister Meles Zenawi's government for the independence of the Oromo region from the rest of Ethiopia.
Police also suspected opposition groups, which were accused of trying to plot a coup after disputed elections last year.