Armenia says a ceasefire with neighbouring Azerbaijan over the breakaway region of Nagorno-Karabakh no longer exists, describing frequent skirmishes at the front line as "war".
Artsrun Hovhannisyan, a spokesman of Armenia's defence ministry, said on Tuesday that Azerbaijan was using "all existing armaments: tanks, howitzers, and anti-aircraft artillery" against Armenian soldiers in the disputed region.
"What we have today is a war," said Hovhannisyan. "We must use the word 'war' as there is no ceasefire anymore."
Azerbaijan responded with counter-accusations, blaming Armenia for the recent escalation.
"Ceasefire violations are taking place because of the illegal presence of Armenian forces in the occupied lands of Azerbaijan," Hikmat Hajiyevm, Azerbaijan's foreign ministry spokesman, told the AFP news agency.
"Armenia has to withdraw from the seized lands ... only afterwards the sustainable peace can be guaranteed in the region."
RELATED: Tensions reignite in the Nagorno-Karabakh conflict
Ethnic Armenian separatists backed by Yerevan seized control of the mountainous Nagorno-Karabakh region - part of Azerbaijan during the Soviet period - during a war the early 1990s that claimed the lives of about 30,000 people.
A 1994 ceasefire failed to lead to a peace deal, with clashes erupting regularly and the two countries remaining on a war footing.
Energy-rich Azerbaijan, whose military spending exceeds Armenia's entire state budget, has repeatedly threatened to take back the breakaway region by force if negotiations fail to yield results.
Moscow-backed Armenia says it could crush any offensive.
Earlier this month, Azerbaijani tanks shelled positions in the Nagorno-Karabakh region for the first time in more than 20 years, the rebel defence ministry said.
The Organisation for Security and Cooperation in Europe (OSCE) mediators recently warned "the status quo has become unsustainable".
Talks in Switzerland at the weekend between the leaders of Azerbaijan and Armenia - Ilham Aliyev and Serzh Sarkisian, respectively - over the future of the disputed region appeared to have brought no tangible results.
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