STEPANAKERT, Azerbaijan (AFP) - Azerbaijan and Armenian separatists in Nagorny Karabakh on Tuesday announced a ceasefire after four days of bloodshed, as international powers scrambled to end the worst violence in decades over the disputed region.
The two sides said they had agreed to halt fighting from 0800 GMT (4pm Singapore time) after clashes since Friday left at least 73 people dead, but Armenia's defence ministry claimed there was still "sporadic shooting" going on.
Key regional powerbroker Russian President Vladimir Putin called the leaders of ex-Soviet Armenia and Azerbaijan after the ceasefire agreement and told them to "ensure" an end to the violence.
"Putin called on both sides to urgently ensure a complete cessation of military hostilities and respect for the ceasefire," the Kremlin said in a statement after Putin spoke to the two presidents separately by telephone.
On a visit to a hospital to meet wounded soldiers, Azerbaijan's President Ilham Aliyev said the conflict could still be resolved peacefully if Armenia's leadership "behaves sincerely at the negotiating table".
The so-called Minsk Group of the US, French, and Russian ambassadors to the Organisation for Security and Cooperation in Europe (OSCE), which has long mediated Karabakh peace talks, also urged both sides to respect the truce after a meeting in Vienna.
The Minsk Group co-chairs "stressed that it is important to return to the political process on the basis of a sustainable ceasefire," a statement said.
In a flurry of diplomacy the mediators are heading to the region to shuttle between the two warring sides, while Russian Prime Minister Dmitry Medvedev is set to travel to Yerevan and Baku in the coming days.
Russia's foreign ministry also said that the top diplomats from Russia, Iran and Azerbaijan will focus on the conflict when they meet for planned talks in Baku on Wednesday, RIA Novosti reported.
On the ground, an AFP photographer in the frontline Azeri town of Terter said that both sides appeared to have stopped shelling Tuesday afternoon after a night of sporadic artillery fire across the front.
At the Karabakh army checkpoint near the Iranian border, shelling halted as well around midday, another AFP photographer said.
The fragile truce comes after Azerbaijan's army claimed to have snatched control of several strategic locations inside the Armenian-controlled territory, effectively changing the frontline for the first time since an inconclusive truce ended a war in 1994.
Baku said it took control of strategic Lala-Tepe and Talysh heights and the village of Seysulan but Yerevan dismissed the claims as "untrue."
"Even if certain Armenian positions were at some point taken by Azeris, now they are all returned under Karabakh's control," Armenia's defence ministry spokesman, Artsrun Hovhannisyan, told AFP.
Baku had announced a unilateral truce on Sunday, but it failed to stop the fighting, and on Monday Armenia said a ceasefire would only be possible if both sides return to their previous positions.
In updated death tolls given on Tuesday evening for the fighting Azerbaijan's authorities told AFP that 31 soldiers and two civilians on their side had died, while rebel Karabakh officials said 35 Armenian fighters and five civilians were killed.
Both sides accused each other of starting the latest outbreak of violence and it has sparked concern of a wider conflict in the region that could drag in Russia and Turkey.
While ex-Soviet master Moscow has sold arms to both sides and treads a careful line between the two, it has a military alliance with, and base in, Armenia and far closer ties to Yerevan.
Turkey - which is locked in a feud with Moscow after Ankara downed a Russian warplane in Syria in November - has pledged its full support for traditional ally Azerbaijan.
Russia and the United States have called for the fighting to end but Turkey predicted that Azerbaijan will "one day" take back its territory and Prime Minister Ahmet Davutoglu vowed to stand by Baku "until the apocalypse."
Security alliance Nato - of which Turkey is a member - said that it welcomed "the reports of the cessation of hostilities" and called on all sides to "show restraint and prevent any new escalation".
Separatists backed by Yerevan seized control of mountainous Nagorny Karabakh, a majority ethnic Armenian region lying inside Azerbaijan, in an early 1990s war after the Soviet Union crumbled that claimed some 30,000 lives.
The sides have never signed a peace deal despite the 1994 ceasefire and sporadic violence on the line of contact regularly claims the lives of soldiers on both sides, though the latest outbreak represents a serious escalation.
Energy-rich Azerbaijan, whose military spending exceeds Armenia's entire state budget, has repeatedly threatened to take back the breakaway region by force.