YEREVAN, Armenia (AP) — Leaders of Azerbaijan and Armenia brushed off the suggestion of peace talks Tuesday, accusing each other of obstructing negotiations over the separatist territory of Nagorno-Karabakh, with dozens killed and injured in three days of heavy fighting.

In the latest incident, Armenia said one of its warplanes was shot down by a fighter jet from Azerbaijan’s ally Turkey, killing the pilot, in what would be a major escalation of the violence. Both Turkey and Azerbaijan denied it.

The international community is calling for talks to end the decades-old conflict between the two former Soviet republics in the Caucasus Mountains region following a flareup of violence this week. It centers on Nagorno-Karabakh, a region that lies within Azerbaijan but has been under the control of ethnic Armenian forces backed by the Armenian government since 1994 at the end of a separatist war.

Azerbaijani President Ilkham Aliyev told Russian state TV channel Rossia 1 that Baku is committed to negotiating a resolution but that Armenia is obstructing the process.

“The Armenian prime minister publicly declares that Karabakh is (part of) Armenia, period. In this case, what kind of negotiating process can we talk about?” Aliev said. He added that according to principles brokered by the Minsk group, which was set up in 1992 to resolve the conflict, “territories around the former Nagorno-Karabakh autonomous region should be transferred to Azerbaijan.”

Aliev noted that if Armenian Prime Minister Nikol Pashinyan says “that Karabakh is Armenia and that we should negotiate with the so-called puppet regime of Nagorno-Karabakh, (he is) trying to break the format of negotiations that has existed for 20 years.”

Pashinyan, in turn, told the broadcaster that “it is very hard to talk about negotiations … when specific military operations are underway.” He said there is no military solution to the conflict and called for a compromise.

But first, Azerbaijan must “immediately end (its) aggression towards Nagorno-Karabakh and Armenia,” Pashinyan said. “We all perceive this as an existential threat to our nation, we basically perceive it as a war that was declared to the Armenian people, and our people are now simply forced to use the right for self-defense.”

Since Sunday, the Nagorno-Karabakh Defense Ministry reported 84 servicemen were killed. Aliyev said 11 civilians were killed on its side, although he didn’t detail the country’s military casualties.

Both countries accused each other of firing into their territory outside of the Nagorno-Karabakh area on Tuesday.

The separatist region of about 4,400 square kilometers (1,700 square miles), or about the size of the U.S. state of Delaware, is 50 kilometers (30 miles) from the Armenian border. Soldiers backed by Armenia also occupy some Azerbaijani territory outside the region.

Armenia also alleged that Turkey, which supports Azerbaijan, was involved. “Turkey, according to our information, looks for an excuse for a broader involvement in this conflict,” Pashinyan said.

The Armenian military said an SU-25 from its air force was shot down in Armenian airspace by a Turkish F-16 fighter jet that took off from Azerbaijan, and the pilot was killed.

The allegation of downing the jet was “absolutely untrue,” said Fahrettin Altun, communications director for Turkey’s president. Azerbaijani officials called it “another fantasy of the Armenian military propaganda machine.”

Turkish President Recep Tayyip Erdogan urged Armenia to withdraw immediately from the separatist region, and Turkish Foreign Minister Mevlut Cavusoglu said Turkey is “by Azerbaijan’s side on the field and at the (negotiating) table.”

Armenian officials said that Turkey, a NATO member, is supplying Azerbaijan with fighters recruited in Syria and weapons, including F-16 fighter jets. Both Azerbaijan and Turkey deny it.

Earlier in the day, Azerbaijan’s Defense Ministry said Armenian forces shelled the Dashkesan region in Azerbaijan. Armenian officials said Azerbaijani forces opened fire on a military unit in the Armenian town of Vardenis, setting a bus on fire and killing one civilian.

Armenia’s Foreign Ministry denied shelling the region and said the reports were laying the groundwork for Azerbaijan “expanding the geography of hostilities, including the aggression against the Republic of Armenia.”

German Chancellor Angela Merkel has pushed for “an immediate cease-fire and a return to the negotiating table” in phone calls with the leaders of both countries, her office said.

She told them the Organization for Security and Cooperation in Europe offers an appropriate forum for talks and that the two countries’ neighbors “should contribute to the peaceful solution,” said her spokesman, Steffen Seibert.

U.S. Secretary of State Mike Pompeo said during a visit to Greece that “both sides must stop the violence” and work “to return to substantive negotiations as quickly as possible.”

Russia, which along with France and the United States co-chairs the Minsk group, urged every country to help facilitate a peaceful resolution of the conflict.

“We call on all countries, especially our partners such as Turkey, to do everything to convince the opposing parties to cease fire and return to peacefully resolving the conflict by politico-diplomatic means,” Kremlin spokesman Dmitry Peskov said Tuesday.

Putin spoke to Pashinyan on Tuesday for the second time in three days, urging de-escalation and, like the other leaders, an immediate cease-fire.