Washington: The US military has launched an air strike in Somalia targeting a senior leader of the al Qaeda-aligned al-Shabaab militant group, the Pentagon said.

"The strike took place in the vicinity of Saakow, Somalia," US Defence Department spokesman Mark Wright said in a statement. "At this time, we do not assess there to be any civilian or bystander casualties. We are assessing the results of the operation and will provide additional information, when appropriate, as details become available."

Al Shabaab fighters perform military exercises near Mogadishu, in Somalia. Credit:AP

The Pentagon did not identify the senior leader or say whether the strike was successful.

A senior US defence official said the strike did not target Ahmad Umar, who took over as the top leader of al-Shabab when its previous leader, Ahmed Abdi Godane, was killed in a US air strike in Somalia on September 1. The official spoke on condition of anonymity because he was not authorised to discuss details of the attack by name.