Turkey sharply criticized Armenia on Sunday after clashes between Armenian and Azeri forces, saying Yerevan was an obstacle to peace and vowing to continue its support for Baku.
Armenia declared martial law and mobilized its male population after the clashes, which Yerevan and Baku blamed on each other and in which both sides reported fatalities.
In a statement on Twitter following a phone call with Azeri President Ilham Aliyev, Turkish President Tayyip Erdogan called on Armenian people to stand against leaders who he said were "dragging them to catastrophe", adding that Ankara's solidarity with Baku would "increasingly continue".
"Armenia, which has added another to its attacks against Azerbaijan, has shown once again that it is the biggest threat to peace in the region," Erdogan said, and added that international reaction to the conflict had been insufficient.
Turkey calls on "the entire world to stand with Azerbaijan in their battle against invasion and cruelty," Erdogan said.
Armenia did not immediately respond to the criticism but has said Azeri forces fired first on Sunday.
Azerbaijan and Armenia have long been at odds over the mainly ethnic Armenian region of Nagorno-Karabakh which is in Azerbaijan but declared independence in 1991. A ceasefire was agreed in 1994, but both sides accuse each other of attacks.
Turkey has traditionally backed Muslim-majority Azerbaijan.
Turkish Defence Minister Hulusi Akar said Armenia must immediately cease what he called hostility towards Azerbaijan that could "throw the region into fire".
Presidential spokesman Ibrahim Kalin said Armenia had violated international laws by carrying out attacks and accused it of being "reckless". "We believe this conflict can be resolved through peaceful negotiations, but the Armenian side has shown no interest so far other than continuing to occupy parts of Azerbaijan," he said.