Armenian Prime Minister Nikol Pashinyan on Wednesday ruled out a diplomatic solution to the conflict with Azerbaijan over the Nagorno-Karabakh region, dealing a fresh blow to efforts by world powers to secure a lasting truce.

Hundreds have already been killed in the latest flare-up of fighting over Karabakh, a region of Azerbaijan long controlled by Armenian separatists. The Karabakh conflict "will not have a diplomatic solution for a long time", Pashinyan said in a video message on Facebook, urging Armenians to volunteer for fighting at the front.

"There is victory and there is defeat. There is no middle ground," he said. He said negotiations on the status of Karabakh were now pointless, accusing Azerbaijan of not wanting to compromise. Hikmet Hajiyev, the adviser to Azerbaijani President Ilham Aliyev, said in a statement that Pashinyan's comments "once again demonstrates that Armenia is not interested at all in the peaceful resolution of the conflict".

Azerbaijan and the Armenian separatists who control Karabakh have been locked in a bitter impasse over the fate of the mountainous province since the break-up of the Soviet Union, fighting a war in the 1990s that left 30,000 people dead. Aliyev has said there could only be a ceasefire if Armenia pulled out from Karabakh and all the surrounding regions of Azerbaijan held by Armenian forces.

However, Pashinyan has repeatedly urged international recognition of Karabakh, claiming its inhabitants would not be safe under Azerbaijani rule. His comments came as Russia hosted the foreign ministers of both countries for separate talks on Wednesday in a new bid to find a lasting truce.

Azerbaijani Foreign Minister Jeyhun Bayramov and his Armenian counterpart Zohrab Mnatsakanyan were also due to meet US Secretary of State Mike Pompeo on Friday. However, no trilateral meetings are taking place. A truce was agreed in Moscow earlier this month after 11 hours of talks, but the accord had little impact on the ground.

A second ceasefire agreed on Saturday fell apart almost immediately. Armenia has said more than 800 of its soldiers and 36 civilians have been killed in the flare-up of fighting. Azerbaijan has reported 63 civilian casualties but has yet to disclose military losses. Analysts have said while Azerbaijan has made some gains on the ground it will not be able to swing the balance in the conflict by military means alone.