Russian forces are intensifying their assaults in eastern Ukraine and keeping up the pressure to take the Azot chemical plant in the city of Severodonetsk, the last stronghold in the Luhansk region.

Luhansk Governor Serhiy Haidai said on Friday that 536 people remain trapped in the plant, including children.
Russia says it will set up an evacuation route for civilians to leave the plant, while demanding that soldiers surrender.

Russia's state-run Tass news agency quotes a pro-Russian separatist leader as saying their troops had entered the plant.

Britain's defense ministry says Russia has likely renewed efforts to advance south of Izyum, and to envelop Severodonetsk from the north.

Russian troops have also shelled Lysychansk, the city neighboring Severodonetsk.

Ukraine's public broadcaster on Friday quoted the Luhansk governor as saying the bombardment left at least three people dead. The governor said Russian forces are attacking infrastructure, and have blown up a key highway.

The New York Times reported on Thursday news of a mass grave in Lysychansk. It said it contained bodies of soldiers and civilians killed in the two cities. A Ukrainian soldier is quoted as saying around 300 people were buried there.

The chief prosecutor of the International Criminal Court says he'll open a field office in Ukraine to speed up the investigation of alleged war crimes.

Karim Khan said in a statement, "Every person who picks up a gun, drives a tank or launches a missile should know that they can be held accountable where crimes are committed."

Ukrainian prosecutors say they are looking into allegations of more than 10,000 war crimes.