Up to five people were killed when Ugandan police clashed with opposition supporters who attacked cars carrying African leaders at the inauguration of President Yoweri Museveni.
A government spokesman confirmed at least one death in the capital, Kampala, on Thursday. But local independent TV station WBS reported that five had died when police opened fire on opposition supporters who threw stones at the cars.
The vehicles included a convoy carrying Goodluck Jonathan, the Nigerian president.
"As they came past, protesters threw stones [and] smashed some of the windows," Al Jazeera's Malcolm Webb reported from Kampala on Thursday. "When police moved in to disperse those protesters, somebody was shot."
Museveni, who has held power for 25 years, was sworn in for a fourth term after winning elections that opposition parties said were rigged.
Since the vote, opposition leaders including Kizza Besigye have led a series of protests against high food and fuel prices.
At the same time as the inauguration, a crowd of thousands supporting Besigye had gathered in the capital to welcome him back to Uganda from Kenya.
The crowd began to flee as police used teargas and water cannons to scatter them. Police said they had to move in after crowds started throwing stones at vehicles carrying guests at the inauguration.
"The crowd was dispersed by police and soldiers. They fired tear gas and water cannons and chased people away with sticks," Al Jazeera's Webb said.
Soon after, however, Besigye's supporters regrouped and continued to march towards the capital.
Leaders of Nigeria, Ethiopia, Kenya, Zimbabwe, Tanzania, DRC, Somalia and South Sudan were all present for the inauguration.
Thursday's ceremony marked Museveni's fourth swearing in as Uganda's president, after promising in 2001 to retire from politics.
According to official results from last February's election, Besigye, 55, won 26 per cent of the vote, while Museveni, 62, took 68 per cent.
But Besigye's Forum for Democratic Change (FDC) says the results were falsified, and that both candidates received just under 50 per cent of the vote, an outcome that would have required a run-off.
Museveni has accused the opposition of trying to spread chaos in response to its loss in the election, saying on Tuesday that he planned to introduce constitutional amendments that would see bail prohibited for
certain charges, including rioting and economic sabotage.
Besigye and other opposition politicians have been released on bail after recent protest-related arrests.
The opposition figure had been in Kenya seeking treatment for injuries he suffered in a series of demonstrations against rising food and fuel prices.
Besigye was first taken to hospital in Kampala at the end of April after Ugandan police smashed the windows of his car and sprayed him with tear gas in an incident caught on camera. He was then transferred to a Nairobi hospital.
He told Al Jazeera at the time that he remained committed to non-violent protest.