Several metals and mining companies have stopped paying their electricity bills, threatening winter heating and electricity supplies for households, the head of the country's biggest private electricity producer said in an interview Wednesday.

"We are now facing an increase in payment delays from big consumers, mainly metals and mining companies, both ferrous and nonferrous," Mikhail Slobodin, president of Integrated Energy System, said in a telephone interview.

He declined to elaborate on the companies.

"The industry is using a legal loophole that prevents us from cutting them off from electricity supplies immediately," said Slobodin, who also heads the Council of Electricity Producers, which comprises all major electricity generators.

"The payment delays take the planned money out of the whole financial system of the generators, which strains our winter-period preparation spending," he said.