Nearly 100 people, including civilians, have died as battles rage on between Armenian and Azerbaijani forces over the disputed Nagorno-Karabakh region.
The mountainous enclave is recognised as part of Azerbaijan, but has been run by Armenians since a war ended in 1994.
The self-proclaimed republic has reported 84 military deaths since Sunday, as well as civilian victims.
Azerbaijan has not revealed its military losses, but has confirmed seven civilian deaths.
The fighting that started three days ago now appears to be spilling out of Nagorno-Karabakh.
On Tuesday, Armenia’s defence ministry said a passenger bus had been hit by an Azerbaijani drone in the eastern Armenian city of Vardenis. There were no reports of casualties.
Azerbaijan earlier said two Azerbaijani civilians had been killed in Armenian shelling in Azerbaijan on Monday, following the deaths of five people from the same family a day earlier.
The fighting is the heaviest seen in the conflict since 2016, and later on Tuesday the UN Security Council is due to hold emergency talks on the issue.
Both Armenia and Azerbaijan – who have already mobilised more soldiers and declared martial law in some areas – blame each other for starting the fighting.
There are growing concerns that other countries may get directly involved in the conflict in the strategic Caucasus region.
Turkey has already openly backed Azerbaijan, while Russia – which has a military base in Armenia – has called for an immediate ceasefire.
Nagorno-Karabakh – key facts
- A mountainous region of about 4,400 sq km (1,700 sq miles)
- Traditionally inhabited by Christian Armenians and Muslim Turks
- In Soviet times, it became an autonomous region within the republic of Azerbaijan
- Internationally recognised as part of Azerbaijan, but majority of population is ethnic Armenian
- An estimated one million people displaced by war in 1988-1994, and about 30,000 killed
- Separatist forces captured some extra territory around the enclave in Azerbaijan
- Stalemate has largely prevailed since a 1994 ceasefire
- Turkey openly supports Azerbaijan
- Russia has military base in Armenia