FILE PHOTO: Ugandan President Yoweri Kaguta Museveni delivers a speech during the launch of the National Dialogue committee in Juba, South Sudan May 22, 2017. REUTERS/Jok Solomun

KAMPALA (Reuters) - Ugandan police have arrested 10 youths for staging an illegal rally to oppose a planned constitutional amendment to allow President Yoweri Museveni, one of the world’s longest serving rulers, to run for a fresh term.

Police spokesman Emirian Kayima said on Monday the youths were detained in the capital Kampala as they mobilized support and distributed fliers with messages opposed to the amendment.

“They were involved in an illegal assembly. They did not inform police ahead of time that they were going to hold a rally,” he told Reuters, adding that they being questioned and would be taken to court.

Museveni, 73, came to power in 1986 and is barred from seeking re-election under a law that limits presidential candidates to 75 years of age and under.

The next presidential election is in 2021. Uganda is Africa’s biggest coffee exporter and a prospective oil producer.

Plans are underway to change the constitution so Museveni can be eligible, a move that has stirred anger.

Critics say Museveni uses the security forces to maintain power. Opposition leaders and activists are often jailed, rallies and meetings are often banned and some are broken up with teargas and beatings.

Museveni has not said whether he intends to stand again and his officials say the removal of the age cap is for the benefit of future leaders and not Museveni specifically.