The United States on Tuesday opened three days of peace talks between Armenia and Azerbaijan, its latest attempt to quell a conflict that has flared repeatedly.

Secretary of State Antony Blinken opened closed-door talks with the adversaries' foreign ministers at a State Department office just outside Washington, the second such negotiation session he has led in as many months.

"We continue to believe that peace is within reach and direct dialogue is the key to resolving the remaining issues and reaching a durable and dignified peace," State Department spokesman Matthew Miller said ahead of the talks, which he added would cover "very sensitive" areas.

Russia has historically been the mediator between the two former Soviet republics but the United States and European Union have been increasingly active as Moscow gets bogged down in its invasion of Ukraine.

Armenia has repeatedly accused Russian peacekeepers of failing to live up to promises to protect ethnic Armenians in line with a 2020 ceasefire negotiated by Moscow after six weeks of fighting left thousands dead.

Russia last week pressed Azerbaijan to let traffic through the Lachin corridor that links Armenia to Nagorno-Karabakh, a predominantly ethnic Armenian area effectively controlled by Yerevan since war during the collapse of the Soviet Union.

The International Committee of the Red Cross said Azerbaijan had blocked access for convoys delivering aid to Karabakh, raising concerns of shortages of food and medicine.

Russia said that Azerbaijan was violating its obligations to allow traffic to flow. Azerbaijan has insisted that civilians and aid convoys can travel through, with the blockade since December nominally staged by Azerbaijani activists to protest illegal mining.