Russian-backed rebels in eastern Ukraine have said they are taking over scores of factories and mines in the region, many of them belonging to a tycoon whose foundation has been the largest provider of humanitarian aid to the war-battered population.
The moves came in the wake of a weeks-long blockade of the east by Ukrainian nationalists and right-wingers.
The blockade has seriously disrupted trade on both sides, cutting off much of the coal shipments to government-controlled territory and impeding shipments from the mills and factories that are the east's economic backbone.
It has raised the already high tensions in Ukraine, where a war between government forces and separatist rebels has killed more than 9,800 people.
The Minsk agreement, a 2015 pact that has been consistently violated, envisions the rebel-held Donetsk and Luhansk regions remaining within Ukraine, although with expanded local powers.
However, a recent surge in fighting, the blockade and Russia's decision last month to recognise passports and other documents issued by the rebels have threatened the goal of reintegrating the regions.
Ukrainian President Petro Poroshenko has spoken against the blockade, but taken no action to break it.
Mr Poroshenko faces considerable opposition from nationalists in parliament, as well as from a bloc descended from the party of the country's former Russia-friendly president, whose flight from power in 2014 prefigured the eastern conflict.
"We are proud that the blockade has hit the pockets of the occupiers. We should call a war and stop business in blood and all trade with the occupied territories," parliament member Semen Semenchenko, a blockade advocate, said.
Donetsk rebel leader Alexander Zakharchenko told local media on Wednesday that in retaliation for Kiev's blockade, the rebels have taken over the management of 40 factories and coal mines.
They include those owned by tycoon Rinat Akhmetov, who is regarded as Ukraine's richest person.
His Metinvest holding company announced last week that it had stopped operations at a steel mill and a coal mine because of the blockade.
Stopping all of the company's operations could throw 20,000 people out of work, Metinvest said.
There were no immediate reports detailing how management was to be taken over by rebels.
Mr Akhmetov's foundation said in a statement on Wednesday that its work in the region was paralysed after rebels blocked access to his Shakhtar FC arena in the rebel capital Donetsk, which hosted the 2012 European football championships and now serves as a warehouse for the relief effort.
Efforts to block the foundation's access to its facilities in Donetsk "is a threat to the lives of Donbass civilians who became hostages of the armed conflict and found themselves on the verge of survival in the heart of Europe in the 21st century".
The foundation says it has given away more than 11 million food packages to local residents.
The separatists do not allow Ukrainian aid, and in recent months have barred virtually all international organisations from operating there.
Russia has been delivering aid to the rebel-controlled east, too, but some of the deliveries ended up in the fighters' hands and, unlike Mr Akhmetov's food packages, Russian aid was not distributed directly to the population.
Russian foreign minister Sergey Lavrov said in comments carried by Russian news agencies that, in view of the blockade, the rebel authorities "hardly had any other choice" other than to seize the businesses.
The Ukrainian government has criticised the blockade, saying it hurts ordinary Ukrainians in the rest of the country by cutting off coal shipments from separatist regions and resulting in power shortages.
Kremlin spokesman Dmitry Peskov told reporters on Wednesday that Moscow is concerned about a worsening humanitarian situation in the east and pledged that it "will do its best to contribute to a de-escalation" in the area.