Witnesses in Somalia's capital say at least 11 people have been killed and 15 others wounded in fighting between rival militia groups.

The fighting broke out in the Sii-Sii area of Mogadishu Sunday when gunmen linked to an alliance of warlords, the Alliance for Restoration of Peace and Counter Terrorism, opened fire on a vehicle belonging to forces loyal to the country's Islamic courts.

Clashes between the same groups have killed at least 90 people since March.

Many Somalis suspect the coalition of warlords is supported by the U.S. government as part of its campaign to end terrorism. The U.S. State Department has said it supports the alliance's objective of rooting out terrorists, but declined further comment.

Somalia has been without an effective central government since 1991, when clan-based factions ousted President Siad Barre.

A transitional government was formed last year but many factional leaders oppose it.

Some information for this report was provided by AP and Reuters.