Armenia Tuesday accused Azerbaijan at the UN top court of having "completed ethnic cleansing" in the former breakaway region of Nagorno-Karabakh, claims dismissed as "cherry picking" by its bitter rival Baku.

The two countries are embroiled in a long-running legal clash at the International Court of Justice (ICJ), just as military tensions are again ramping up following last year's conflict in the disputed mountainous area.

A world away from the fighting, robed lawyers in the gilded halls of the Peace Palace in The Hague are battling over whether the ICJ has jurisdiction in tit-for-tat cases brought by both sides.

Azerbaijan has been violating the International Convention on the Elimination of All Forms of Racial Discrimination (CERD) "for decades," Armenia's ICJ representative Yeghishe Kirakosyan told AFP.

Kirakosyan added: "Azerbaijan has been espousing policies and practices of racial hatred towards ethnic Armenians which have led to escalation and war and the atrocities committed during the war."

"After threatening to do so for years, Azerbaijan has completed the ethnic cleansing of the region," Kirakosyan, representing the Armenian government, told judges in testimony earlier Tuesday.

Baku was "now consolidating it by systematically erasing all traces of ethnic Armenians' presence including Armenian cultural and religious heritage," he said.

Armenia and Azerbaijan fought two wars, in the early 1990s and 2020, before Azerbaijani forces last September retook full control of Nagorno-Karabakh in a lightning offensive that ended three decades of Armenian separatist rule over the enclave.

Tensions have remained high since the Azerbaijani operation that triggered the exodus to Armenia of most of the enclave's entire ethnic-Armenian population of more than 100,000 people.

 'Durable peace' 

 Baku has vigorously denied allegations of "ethnic cleansing", saying Armenians were free to return as long as they agreed to live under Azerbaijani rule.

Elnur Mammadov, Baku's agent at the court, told AFP that Armenia was "abusing" the ICJ to wage what he called a "public media campaign against Azerbaijan."

"We believe this court is being abused by Armenia... without having any genuine attempt to resolve these disputes at the negotiating table, which would be and is the preference of Azerbaijan," he told AFP.

Mammadov urged the ICJ to throw out the case, arguing that what Armenia is alleging against Azerbaijan does not fall under the CERD and therefore the court has no jurisdiction.

"The problem with the evidence presented today (by Armenia)... They were cherry-picked. They ignored the context," he said.

The ICJ, which rules in disputes between states, issued emergency orders in December 2021, calling on both parties to prevent incitement and promotion of racial hatred.

But while the ICJ's orders are binding, it has no enforcement mechanism and tensions grew, culminating in Azerbaijan's lightning offensive last September.

Both Mammadov and Kirakosyan said they believed peace was possible between the two rivals.

"The ultimate goal is peace, a durable peace," Kirakosyan told AFP.

"And the more immediate goal, mid-term goal, is the right to return for the ethnic Armenians that have suffered throughout the decades," he added.

Mammadov said that peace was "absolutely" achievable.

"We believe it's time for peace," he said.

"But in the meantime, we do continue with these proceedings to have the proper assessment of the past events, of the past crimes committed against Azerbaijan."

The proceedings continue for two weeks.