YEREVAN, Armenia (AP) — Heavy fighting between Armenian and Azerbaijani forces over the separatist region of Nagorno-Karabakh continued for a fourth straight day on Wednesday, in the biggest escalation of a decades-old conflict in years that has killed dozens and left scores of others wounded.

Azerbaijan's Defense Ministry said Armenian forces started shelling the town of Tartar on Wednesday morning, damaging “civilian infrastructure” and wounding people, while Armenian military officials reported that Azerbaijani forces were bombing positions of the Nagorno-Karabakh army in the north of the war-torn region.

Armenian officials alleged that Turkish drones and F-16 fighter jets were being used. Turkey has denied supplying Azerbaijan with arms, and Azerbaijan said it didn't have any F-16 jets.

The fighting in Nagorno-Karabakh erupted Sunday and has continued despite mounting calls for a cease-fire from around the globe.

Nagorno-Karabakh 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 following the breakup of the Soviet Union three years earlier.

The region in the Caucasus Mountains 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.

The conflict escalated on Tuesday, with Armenia alleging Turkish involvement and claiming that a Turkish F-16 fighter jet shot down an SU-25 from its air force in Armenian airspace, killing the pilot.

Turkey, which has been vocal about siding with Azerbaijan in the dispute, denied those claims, and so did Azerbaijan.

However, Turkish Foreign Minister Mevlut Cavusoglu said Wednesday that if Azerbaijan requests assistance, Ankara will provide it.

“We have said that if Azerbaijan wants to solve this on the field, we will stand by Azerbaijan. If Azerbaijan makes a request, we would do the necessary. But we see that Azerbaijan has sufficient capacity," Cavusoglu told the Anadolu news agency.

In the meantime, European officials are seeking to bring the opposing sides to the negotiating table.

French President Emmanuel Macron, speaking on Wednesday at a news conference in Riga, Latvia, called for talks between France, Russia and the United States — the three countries co-chair the Minsk group, set up in 1992 by the Organization for Security and Cooperation in Europe to resolve the conflict — to mediate.

“I will speak to President (Vladimir) Putin tonight and, I think, President (Donald) Trump tomorrow to discuss and propose an exit strategy” for the crisis, Marcon said.

The French president also condemned recent comments from Turkey as “reckless and dangerous" and said he was "extremely preoccupied by the belligerent messages from Turkey in the past hours.”

___

Daria Litvinova in Moscow, Suzan Fraser in Ankara, Turkey, and Sylvie Corbet in Paris contributed to this report.