Head of the board of NJSC Naftogaz of Ukraine Yuriy Vitrenko called for closing the sky at least over humanitarian hubs and nuclear facilities in Ukraine.

"The best option is to have a no-fly zone over the whole of Ukraine, but at least the sky should be closed over the humanitarian part, over that part of the territory of Ukraine through which humanitarian assistance is provided, and where there are many displaced persons," he told a press conference in Lviv on Friday.

"Also, such a zone is important over nuclear power plants. This is important not only for Ukraine, but for the entire region. Damage to a nuclear power plant can lead to a disaster not only in Ukraine, but also in other countries," Vitrenko said.