Residents also said at least one other person was killed in a shooting elsewhere in Mandalay.
At a news conference in the capital Naypyitaw, the military presented a video of a former political colleague of Ms Suu Kyi who claimed he had handed over large amounts of cash and gold to her personally, in what the military has characterised as corruption.
Such allegations have been previously denied by Ms Suu Kyi’s lawyer.
The independent Assistance Association for Political Prisoners has verified 261 protesters’ deaths nationwide but says the actual total, including cases where verification has been difficult, is probably much higher.
It said 2,682 people have also been arrested or charged since the coup, with 2,302 still detained or sought for arrest.
In its news conference, the military presented displays of seized homemade weapons and videos of street battles to argue that the demonstrators are violent and that its efforts to stop them are justified.
However, in the weeks since the February 1 takeover, protesters only started using organised violence after more than 100 demonstrators had been shot dead by police and soldiers.
The allegations against Ms Suu Kyi made by former Yangon Chief Minister Phyo Min Thein were first mentioned by the military several weeks ago.
Myanmar police use teargas on protesters in Yangon
Last week the military-controlled Myawaddy TV station aired a similar video with a construction magnate who also claimed to have made large payoffs to Ms Suu Kyi. That video was replayed at Tuesday’s news conference.
No supporting evidence for the allegations has been offered, and they are generally dismissed as an effort by the military to frame Ms Suu Kyi so she can be discredited and tried on a serious criminal charge. She is already being held on several more minor charges.
Protests against the military coup have been growing with the military’s response becoming increasingly violent.
“We stand with the people of Myanmar in calling for an immediate end to military repression, the release of Aung San Suu Kyi and others, and the restoration of democracy,” said Mr Johnson on Twitter.
Additional reporting by Associated Press.