Residents of Kismayo say renewed clan warfare threatens the future of the port, where African Union and Somali troops earlier this week pushed out Islamic extremists.

Kismayo was the last bastion controlled by al-Shabab, the radical Islamists allied to al-Qaida who taxed goods coming into the port to fund their activities.

Residents say bitter clan rivalry may hamper the creation of a new administration needed to run the city and port.

The clan rivalry centers on control of revenues from the port, one of Somalia's most lucrative business hubs.

The top U.S. official on Africa, Johnnie Carson, this week urged the Mogadishu government and African Union forces to "go in very quickly and establish political stability and a political system that takes into account the various clan and sub-clan interests."