The United States is sending FBI investigators to Ethiopia to look into Saturday's grenade attack on a political rally.

The offer of help was made during talks between the US Under Secretary of Commerce, Gilbert Kaplan, and the Ethiopian Foreign Minister, Workneh Gebeyehu.

Dozens of people have been arrested in connection with the blast, including the deputy chief of police in the capital, Addis Ababa.

Two people were killed and more than 150 were wounded at the mass rally called in support of the reform agenda of Prime Minister Abiy Ahmed.

The US is a longstanding ally of Ethiopia.