Militiamen have prevented the head of Somalia's transitional national government, Abdulkassim Salad Hassan, from embarking on a planned trip to Libya.
Hassan only controls small parts of Somalia
He and senior members of his administration were confronted by a former bodyguard as they prepared to leave from an airport 80km south-west of the capital, Mogadishu.
Some of Mr Hassan's former bodyguards reportedly demanded money before allowing him to fly.
A number of shots were fired into the air and the delegation returned to Mogadishu.
Correspondents say the incident is a vivid reminder of the lack of authority exerted by the transitional government, whose powerbase is confined to small pockets of the country.
Somalia has been without an internationally recognised central government since the overthrow of President Siad Barre in 1991.
Rival warlords and clans run different parts of the country.
The BBC's Hassan Barise in Mogadishu says that the transitional government does not control any of the economic installations, such as ports and airports around the capital.
He says this has prevented Mr Hassan's administration from generating enough revenue to function normally.