Phnom Penh City Hall has banned drones and told food sellers and balloon sellers not to use gas containers among crowds during the Water Festival.
Authorities fear accidents from gas explosions during the three-day festival, which starts on Thursday.
City Hall spokesman Met Meas Pheakdey said: “We are not allowing the use of gas because the safety and security of people is a priority.”
Food sellers could find another way to conduct their business. “We explained this to them and hope they will understand,” he said.
Authorities say they expect the Water Festival to take place smoothly and safely.
Mr Meas Pheakdey confirmed that drone cameras were also banned.
Festival organisers say 270 boats have registered to race, up from the 257 boats last year. At night, 14 illuminated boats will be on display.
Touch Naruth, bodyguard unit chief and deputy national police chief, said last week that some roads would be closed from 1pm until 12am to make it easier to walk around at the festival.
Vehicles would be banned from streets 130, 5, 154, 224, 214, 51, 294 and parts of Norodom and Sothearos boulevards.