Ugandan presidential candidate and pop star Bobi Wine says one of his bodyguards was killed when military police ran him over.
Wine said the killing happened when his convoy was taking a journalist, who had been wounded by police, to seek medical help.
The military police responded by saying the bodyguard had fallen from a speeding car.
Wine, whose real name is Robert Kyagulanyi, has emerged as the strongest challenger to President Yoweri Museveni, 76, in the presidential election on January 14.
"I regret to announce the murder of my security team member Francis Senteza Kalibala aka Frank," said Wine.
"He was deliberately run over by military-police truck, No. H4DF 2382, which blocked us in Busega on our way to Rubaga to get Kasirye Ashraf emergency medical attention."
The Ugandan military's spokeswoman wrote on Twitter late on Sunday that the bodyguard had not been hit by a military police vehicle.
"UPDF (Ugandan People's Defence Force) would like to clarify that the late Senteza ... was not knocked by a Military Police Vehicle as purported, but rather fell off a speeding car ... he tried to jump to (sic) but fell off."
Police spokesman Fred Enanga did not respond to a request for comment on the bodyguard.
He had earlier told Reuters that supporters of Wine had gathered on Sunday in Masaka, 125 km southwest of the capital Kampala.
Wine had attended a church service in the town, he tweeted.
Enanga said the supporters were "a violent group" but gave no further details on what they were doing.
"Teargas was used to quell the violence. The journalists were regrettably caught up during the process of dispersing the violent group," he said.
He said one of the journalists, from television station Ghetto TV, sustained a serious injury above his left eye "allegedly from a (teargas) canister".
Ashraf Kasirye was hospitalised at Masaka Referral Hospital then transferred to Kampala, he said.
"He is in a critical condition," Wine later wrote on Twitter of Kasirye's injury. "We are hoping against hope that he will live."
All three journalists who were injured were wearing bulletproof vests and helmets marked "PRESS", local reporter Culton Scovia Nakamya of BBS TV told Reuters.
Masaka is one of 11 areas where campaigning has been suspended because of coronavirus risks - although government critics say the real reason is the opposition's popularity in these areas.