Nato and EU silent on Turkey, despite Armenia's appeal

"All must now work towards a sustainable political solution. Armenia and Azerbaijan should resume negotiations to reach a peaceful settlement," Stoltenberg added.

Stoltenberg will also speak with Turkey's defence chief in a video-conference with all Nato ministers on Thursday and Friday.

The talks will cover Turkey's naval confrontations with Greece in the eastern Mediterranean, Stoltenberg told press earlier on Wednesday.

He also criticised Ankara for buying Russian anti-aircraft missiles, but he did not mention the South Caucasus at all.

Meanwhile, the president of the EU Council, representing EU states, Charles Michel, issued a similar message after also meeting Sarkissian in Brussels.

"Parties must respect the ceasefire and return to the negotiating table without preconditions," Michel said on Wednesday.

"External interference is unacceptable," he added, in an oblique reference to Turkey.

For his part, Sarkissian had flown to the Nato and EU capital on a personal mission to create international pressure on Ankara.

France and others have accused Turkey of supplying Syrian mercenaries and high-tech drones to help its ally Azerbaijan, in allegations Ankara denies.

Turkey is also giving Azerbaijan moral support, with Turkish president Recep Tayyip Erdoğan the only regional leader not calling for an end to violence.

And if the Western and European allies wanted peace, then the way to get it was to lean on their fellow Nato member and EU enlargement hopeful, Armenia's Sarkissian said.

"There is a third party [in the conflict], which is supporting Azerbaijan diplomatically and through serious military [aid], participating in the operations, and bringing Islamist terrorists to the region, and unfortunately, that third party is a Nato member. Unfortunately ... this third party is Turkey," Sarkissian said.

"If Nato-member Turkey stopped being a party to the conflict, made its contribution to the ceasefire regime, and understood that there is a need for a peaceful settlement, we would be able to maintain the ceasefire, after which we would sit at the negotiating table and find a peaceful resolution," he added.

Fighting erupted over the Armenia-occupied Nagorno-Karabakh region in Azerbaijan in September.

It has claimed more than 800 lives, including many civilian victims, in the most intense violence since full-scale war ended in 1994.

Turkey aside, the conflict threatens to drag in Russia, which has a defence pact with Armenia under the Collective Security Treaty Organisation - a post-Soviet military alliance.

It also risks pulling in Iran, which does not want Turkish or Syrian rebel forces on its northern border and whose territory is being hit by stray shells.

France is meant to lead EU diplomacy on the crisis via its co-presidency of the Minsk Club - a diplomatic forum for Armenia-Azerbaijan peace talks.

But that structure has remained largely inert for the past 26 years.

Two Russian-brokered ceasefires have also unravelled in recent days, moments after they were agreed, despite Russia's vast military superiority in the region.