Russia and France stepped up calls for an immediate ceasefire between Azerbaijan and ethnic Armenian forces on Thursday as the death toll rose in the heaviest clashes around the Nagorno-Karabakh region since the 1990s.
The Kremlin said President Vladimir Putin and French President Emmanuel Macron had discussed moves that the Organization for Security and Co-operation's (OSCE) Minsk group, which mediates in the conflict, could take to end the fighting.
Russia has also offered to host the foreign ministers of Armenia and Azerbaijan for talks on ending fighting that flared on Sunday, reviving a decades-old conflict over the mountainous enclave in the South Caucasus region.
Azerbaijan's general prosecutor's office said Armenian shelling had killed a civilian in the Azeri town of Terter on Thursday morning and badly damaged the town's train station.
Armenia's defence ministry spokeswoman said the situation remained tense and Azerbaijan's forces had tried to regroup but had been prevented from doing so.
Armenia said two French nationals working for France's Le Monde newspaper had been wounded during Azeri shelling of the Armenian town of Martuni and taken to hospital. An Armenian government source said they were in grave condition.
Television footage released by the Ankara-based Anadolu Agency showed reporters running for cover behind a wall at an unidentified location in Nagorno-Karabakh after what it said was Armenian shelling. Loud blasts could be heard in the background.
Dozens have been reported killed and hundreds wounded since Sunday in the fighting over Nagorno-Karabakh, a region inside Azerbaijan that is administered by ethnic Armenians. It broke away in a 1991-94 war that killed 30,000 people, but is not recognised internationally as an independent republic.
The re-eruption of a "frozen conflict" dating back to the collapse of the Soviet Union has raised concerns about stability in the South Caucasus, a corridor for pipelines carrying oil and gas to world markets, and raised fears that regional powers Russia and Turkey could be drawn in.
"President Macron and Putin agreed on the need for a joint effort to reach a ceasefire in the framework of Minsk," Macron's office said in a statement after the two leaders spoke by telephone late on Wednesday.
The Kremlin said there was no alternative to using "political and diplomatic methods" to resolve the crisis.
Russia and France co-chair the Minsk group with the United States. The group has not met since the latest fighting began.
Macron's office said he and Putin "also shared their concern regarding the sending of Syrian mercenaries by Turkey to Nagorno-Karabakh".
The Kremlin made no mention of this and Turkey has denied sending mercenaries. But Russia, which has a military base in Armenia, said on Wednesday that Syrian and Libyan fighters from illegal armed groups were being sent to Nagorno-Karabakh.
Turkey, a close ally of mainly Muslim Azerbaijan, has said it will "do what is necessary" to support Azerbaijan. Macron, whose country is home to about 600,000 people of Armenian origin, has accused Turkey of "warlike" rhetoric.
Russia has said it will continue to work on the crisis both independently and with other representatives of the Minsk group.
A German government source said European Union leaders would consider the conflict at a summit starting in Brussels later on Thursday.
France's junior European affairs minister, Clement Beaune, said the EU must give "signals of resolve" against Turkey and that this could mean possible sanctions.