Ethiopian forces engaged in fierce clashes with al-Shabaab fighters near the town of Rab Dhuure in western Somalia on Sunday morning, local residents said.

At around 9am (0600 GMT) local residents heard large explosions near the town of Rab Dhuure in Bakool region, around 20 kilometres (12 miles) from the Ethiopia border.

Al Shabaab claimed to have ambushed a large convoy of Ethiopian troops, who are operating in the area as part of regional efforts to wipe out the al Qaeda-affiliated group.

"We heard about three huge explosions and then an exchange of heavy guns followed," said local resident Hassan Abdulle.

"It was a fierce fighting with shells and other weapons but we don't know the details," Fatuma Ali, who lives in Rab Dhuure, said.

Ethiopia's army and Somali authorities did not respond to requests for comment.

In February Djibouti, Ethiopia and Kenya agreed to begin what they described as "search and destroy" operations against al-Shabaab, in addition to the African Union-mandated peacekeeping force, which is expected to leave Somalia by the end of next year.