Turkish President Recep Tayyip Erdogan on Wednesday blamed Armenia for the deadliest clashes with Azerbaijan since their 2020 war over disputed Nagorno-Karabakh.

Armenia on Wednesday said Azerbaijan's forces were occupying 10 square kilometres (almost four square miles) of its territory as result of border clashes that have killed dozens of soldiers on both sides.

Turkey is a key regional broker with close ties to Azerbaijan and historically poor relations with Armenia.

Erdogan blamed the latest escalation on unspecified violations by Armenia of a Russian-brokered agreement that brought an end to the 2020 war.

The deal allowed Azerbaijan to take control of large parts of Nagorno-Karabakh it had lost in a 1990s war.

"We find the situation we are in -- which is the result of violations of the deal reached after the war ended with Azerbaijan's victory -- as unacceptable," Erdogan told a public rally.

"It will, of course, have consequences for Armenia, which did not fulfil the agreement's conditions and constantly displayed an aggressive attitude."

Armenia has confirmed the death of more than 100 soldiers and Azerbaijan has reported 50 fatalities.

The toll could still mount due to reports of continuing exchanges of fire.

Turkey is Azerbaijan's main weapons supplier and a backer of Baku's cause on the diplomatic stage.

The violence threatens to derail a nascent effort by Turkey and Armenia to strike a reconciliation agreement that could bolster trade and travel between the neighbouring states.

Turkey's relations with Armenia -- which relies on diplomatic and military backing from Russia -- have been effectively frozen because of Ankara's refusal to recognise the genocide of Armenians by the Ottomans during World War I.

Erdogan is expected to meet Russian President Vladimir Putin at a regional summit in Uzbekistan on Friday.