Secretary of State Antony Blinken promised US support for the peace process between Armenia and Azerbaijan in separate conversations with the two countries' leaders over the weekend, while calling for the opening of a road leading to disputed territory.

Armenia and Azerbaijan are engaged in a decades-long standoff, and have fought two wars over the mountainous enclave of Nagorno-Karabakh that have left tens of thousands dead.

During Blinken's talk with Azerbaijan's President Ilham Aliyev Sunday, he "expressed the United States' deep concern that Azerbaijan's establishment of a checkpoint on the Lachin corridor undermines efforts to establish confidence in the peace process," State Department spokesman Matthew Miller said in a statement.

Azerbaijan established a checkpoint at the entry of the Lachin corridor last weekend, which Armenia denounced as a breach of the latest ceasefire between the two arch-foes.

The area is the only land link between Armenia and the disputed Nagorno-Karabakh enclave.

Blinken "emphasized the importance of reopening the Lachin corridor to commercial and private vehicles as soon as possible," the statement added.

He conveyed the United States' support for the Azerbaijan-Armenia peace process to Aliyev, Miller said, and "shared his belief that peace was possible."

The day before, Blinken also spoke with Armenia's Prime Minister Nikol Pashinyan, Miller said in a separate statement Saturday.

The secretary of state also talked about "the importance of Armenia-Azerbaijan peace discussions" and "pledged continued US support," according to Miller.

"Secretary Blinken reiterated that direct dialogue and diplomacy are the only path to a durable" solution.

Moscow brokered a ceasefire between Yerevan and Baku after the latest bout of fighting in 2020 and posted peacekeepers along the Lachin corridor.

With Russia bogged down in Ukraine and unwilling to strain ties with Azerbaijan's key ally Turkey, the United States and European Union have sought to steer a thaw in ties.