Thousands of people have taken to the streets of Djibouti to call for President Ismael Omar Guelleh to step down.
The demonstrators were reportedly monitored closely by security forces in riot gear.
Mr Guelleh's family has governed the Red Sea city state since independence from France in 1977. The United States has a large military base in Djibouti.
The constitution was last year amended, to let Mr Guelleh seek a third term.
Some of the protesters say they will stay in a stadium until Mr Guelleh, 63, leaves power in the Somali-speaking country.
Elections are due in April. Mr Guelleh was re-elected unopposed in 2005.
