Azerbaijan yesterday said it would stop fighting Armenian-backed separatists over the breakaway Nagorno-Karabakh region after two days of clashes, but the other side denounced Baku's gesture as hollow and said violence was continuing.

Nagorno-Karabakh, which lies inside Azerbaijan but is controlled by ethnic Armenians, has run its own affairs with heavy military and financial backing from Armenia since a separatist war ended in 1994.

But the situation along the tense "contact line” deteriorated in recent weeks, leading to clashes in which dozens were killed that drew international calls for an immediate ceasefire. Both sides also reported civilian casualties.

Baku pledged to "reinforce" several strategic positions it claimed to have "liberated" inside the Armenian-controlled region yesterday, which is internationally recognised as part of Azerbaijan.

The Armenian-backed separatist defence ministry in Karabakh - which claims independence but is heavily backed by Yerevan - said they were willing to discuss a ceasefire but only if it saw them regain their territory.

A spokesman for the Karabakh presidency, David Babayan, told AFP that fighting had not halted along the frontline.

"Fierce fighting is under way on southeastern and northeastern sectors

of the Karabakh frontline," he said.

Fierce clashes left at least 18 Armenian and 12 Azerbaijani soldiers dead Saturday after the two sides accused each other of attacking with heavy weaponry across the volatile frontline.

Armenia's President Serzh Sarkisian called the clashes the "largest-scale hostilities" since a 1994 truce ended a war in which Armenian-backed fighters seized the territory from Azerbaijan.

Azerbaijan said one of its helicopters was shot down as its forces took control of several strategic heights and a village in Armenian-controlled territory.

Both Russia and the West appealed to all sides to show restraint, with key regional power broker President Vladimir Putin calling for an" immediate ceasefire".

US Secretary of State John Kerry urged the arch foes to return to peace talks under the auspices of the Organisation for Security and Cooperation in Europe (OSCE), reiterating "there is no military solution to the conflict".

Turkish President Recep Tayyip Erdogan meanwhile vowed to back traditional ally Azerbaijan "to the end" in the conflict.

Moscow-backed Armenia says it could crush any offensive.

The conflict over Nagorno-Karabakh, a region home to around 150,000 people on the southern Armenian-Azeri border, broke out in the dying years of Soviet Union. By the time the 1994 ceasefire was brokered, some 30,000 people had been killed in