Major violations of oil storage rules may be a cause of the fire on the premises of an oil depot operated by BRSM in the urban-type settlement of Hlevakha in the Vasylkivsky district of the Kyiv region, Advisor to the Ukrainian Interior Minister Zorian Shkiriak has said.

"Technological factors are also being scrutinized, and arson is not ruled out either. Detectives will establish the truth. It is impossible to name the precise cause of this tragedy now. The fire is still raging," he wrote on Facebook on Tuesday.

Previously BRSM-Nafta Strategic Marketing Department Director Oleksandr Melnychuk told Interfax that the flames had spread throughout the oil depot and practically reached an adjacent oil terminal operated by KLO.

"The fire has not been put out; the entire oil depot is ablaze… and the flames have practically reached the adjacent KLO oil terminal. We are doing our best, 40,000 kilograms of foam-forming mixture were delivered here at night. The fire department appeared to be unable to deal even with the initial stage of the fire," he said.

Four employees of the oil depot have been admitted to hospital, Melnychuk said, adding that he knew nothing about injured firemen.

The BRSM-Nafta executive said the company had not assessed losses incurred from the fire and viewed that assessment as a matter of lesser significance.