Ugandan police said they had released the country's main opposition leader and several of his allies late on Thursday after detaining the group to stop them leading an anti-government rally in the capital.
Veteran leader Yoweri Museveni last year accused rival Kizza Besigye of inciting unrest and cracked down hard on a wave of opposition-led protests led by his one-time political ally.
"We had arrested them as a preventive measure to stop them from causing chaos and disrupting public peace and order," deputy police spokeswoman Judith Nabakooba told Reuters on Friday.
"We later got satisfied that they were no longer a threat to public order and we decided to release them," she said.
Armed police intercepted Besigye, who heads the Forum for Democratic Change (FDC) party, and other opposition politicians on Thursday as they headed towards the demonstration venue.
A protracted standoff ensued, ending after police fired a single teargas canister that scattered a small crowd, and bundled the politicians into vans.
Besigye, who was defeated by Museveni at the ballot box last year for the third time, plans to quit his role as FDC chief to devote more time planning protests, he told Reuters last week.
Semujju Nganda, an opposition lawmaker, vowed the rallies would continue. "We'll never succumb to the ... abuse of the police. Our 2012 momentum has only begun," Nganda told Reuters.
Museveni, once lauded for his liberal economic policies, has faced criticisim from opponents and rights groups for an increasingly autocratic leadership style.