Azerbaijan has promised equal treatment to residents of the majority ethnic Armenian enclave and has sent aid.
Adding to humanitarian concerns, the separatist government said on Tuesday that 13 bodies had been found at the site of a fuel depot explosion on Monday and seven more had died of their injuries.
A statement said 290 people had been hospitalized and “dozens of patients remained in critical condition”.
Armenia’s health ministry said it had sent a team of doctors by helicopter to the rebel stronghold of Stepanakert.
The Azerbaijani president said Baku had also sent medicine to help the injured.
Meanwhile in Brussels, envoys from Baku and Yerevan prepared to meet in the first such encounter since Azerbaijan’s quick defeat of separatist forces last week.
Simon Mordue, chief diplomatic adviser to European Council President Charles Michel, will chair the talks, Michel’s spokesman said.