MOSCOW (AP) — Ukraine's president on Thursday pledged to resume coal supplies from separatist-controlled parts of the country after it was blocked by volunteer battalions, threatening to disrupt the country's power supply.

Fighting in Ukraine's industrial east between government troops and Russia-backed rebels has killed more than 9,800 people since April 2014. Despite the hostilities, Kiev continued to buy coal from areas controlled by separatists as power stations in Ukraine are mostly designed to run on the specific type of coal that is produced there.

Sales were suspended when Ukraine's unruly volunteer battalions and some lawmakers blocked a railroad that brings coal across the front line late last month.

President Petro Poroshenko said that the lack of coal from the east risks leaving entire towns without heating and he pledged to resume the supply.

Prime Minister Volodymyr Groysman said that about nine out of 24 million tons of coal that Ukrainian power stations require every year is imported from the rebel-occupied east. He has held an emergency government session which agreed on a temporary shutdown of some parts of the electricity grid if the supply shortage gets worse.

An Associated Press investigation in 2015 detailed how billionaire Renat Akhmetov, one of Ukraine's richest men, operates factories and coal mines on both sides of the front line, powering the country's economy and pouring hundreds of millions in taxes into government coffers. His steel products, which are finished in rebel territory, are then shipped to the West — where they bring in billions in revenue for Akhmetov that then indirectly props up the separatist government. His companies provide more than 300,000 jobs across Ukraine, most in the rebel-held east.

Poroshenko on Thursday mentioned the same figure when he said this is approximately how many people could lose their jobs if the economic ties between parts of the east and the rest of Ukraine are severed completely. Poroshenko painted a grim picture of what might happen if the factories and coal mines in rebel-occupied Donbass grind to a halt.

"What is better for us: for them to work in the mines, or for them to shoot at us?" Poroshenko asked in a public speech in Kiev. "We are implementing a strategy to restore the country's territorial integrity — returning Donbass to Ukraine's fold and getting Ukraine back to Donbass."