Prime Minister Denys Shmyhal has received a letter from acting Energy Minister Yuriy Vitrenko with a proposal to dismiss Andriy Kobolev, head of the Naftogaz Ukrayiny board, and replace the members of the company's supervisory board, but implementation of these proposals is unlikely, a source in the government said. "There is such a letter. A formal answer will be given," a source told reporters on Tuesday.