Britain is to cut the amount of direct aid it gives to Uganda by £15m ($26m) because of concerns about the country's slow progress to democracy.
Opposition leader Kizza Besigye denies charges of treason and rape
The money will be diverted to aid agencies in the conflict zone of north Uganda, International Development Secretary, Hilary Benn said.
A further £4m is being held back pending the conduct of presidential elections due in February next year.
The announcement follows a similar move by Sweden, which diverted £4.6m.
European governments have expressed concern about the prospects for a fair election following the arrest on treason charges of the main opposition leader, Kizza Besigye.
Northern Uganda is terrorised by rebel fighters who kidnap children and force them to fight.
The Lord's Resistance Army has murdered tens of thousands of people during a 19-year campaign.
They are led by Joseph Kony, who claims he is on a mission from God and wants Uganda's laws to replicate the Ten Commandments.
More than 25,000 children have been abducted and now represent 80% of the rebel force.