BAKU/YEREVAN - Azerbaijan and the breakaway region of Nagorno-Karabakh said on Tuesday they were halting hostilities after four days of intense fighting between them that had prompted warnings the conflict could spiral into all-out war. Reuters was not immediately able to verify whether the fighting - a resurgence of a decades-old conflict over the status of the region - had, in fact, stopped.

The ceasefire announcement came as several European countries urged an end to the fighting, worried that an escalation could cause instability in a region that serves as a corridor for pipelines taking oil and gas to world markets. The fighting has been the bloodiest in years, with Azerbaijan saying 16 of its servicemen were killed in the past 48 hours. Officials in the breakaway region had earlier said 20 of their soldiers were killed since the fighting started. Ex-Soviet states Azerbaijan and Armenia fought a war over the mountainous territory in the early 1990s in which thousands were killed on both sides and hundreds of thousands displaced.

The war ended with a fragile truce in 1994, followed since by sporadic bouts of violence. The ceasefire was shattered over the weekend, with the two sides exchanging heavy fire using artillery, tanks, rocket systems and helicopters.

In a statement on the ceasefire, Azerbaijan’s defence ministry said: “On April 5 at 12:00 (0800 GMT), on the basis of a mutual agreement, military actions on the contact line between the armed forces of Armenia and Azerbaijan are halted.”

An official with the Armenian-backed armed forces of Nagorno-Karabakh told Reuters: “We’ve been ordered to halt fire.”

As late as Tuesday morning, both Azerbaijan and the Armenian-backed separatists had been reporting fresh clashes. An all-out war over Nagorno-Karabakh could drag in the big regional powers, Russia and Turkey. Moscow has a defence alliance with Armenia, while Ankara backs Azerbaijan.

Turkish Prime Minister Ahmet Davutoglu on Tuesday condemned what he said were Armenian attacks, and said Turkey would stand by Azerbaijan. Earlier, Russia’s foreign minister had said Ankara’s support for Baku in the conflict was one-sided.

Nagorno-Karabakh is a mountainous enclave with a large ethnic Armenian population that lies inside the territory of Azerbaijan. The violence was a re-awakening of a long-festering ethnic conflict between the mainly Muslim Azeris and their Christian Armenian neighbours.

Envoys from Russia, France and the United States - who make up a body called the Minsk Group which mediates in the conflict - were planning to head to the region, French Foreign Minister Jean-Marc Ayrault said in Paris. “We can see that military conflict cannot be the solution,” Ayrault told reporters after talks with his German counterpart Frank-Walter Steinmeier.