TEHRAN, April 3. /TASS/. Tehran calls on the parties to the Nagorno-Karabakh conflict to display restraint and avoid any actions that could escalate the situation, Iranian Foreign Ministry spokesman Hossein Jaberi Ansari said on Saturday.

'We invite both of our northern neighbors to restraint and avoiding any action than can turn the situation more difficult," Iran’s IRNA news agency quotes him as saying.

Ansari added that reports of armed clashes in the Nagorno-Karabakh region were "a source of deep concern for the Islamic Republic of Iran."

"We urge Azerbaijan and Armenia to cease clashes promptly and use all their might to restore tranquility and peaceful settlement of differences within the peace groups and under the United Nations," he said.

Neighboring Armenia and Azerbaijan fell out with each other in the late 1980s because of Nagorno-Karabakh, the disputed territory that had been part of Azerbaijan before the Soviet Union break-up but was mainly populated by Armenians.

In 1991-1994, the confrontation spilled over into large-scale military action for control over the enclave and some adjacent territories. Thousands left their homes on both sides in a conflict that killed 30,000. A truce was called between Armenia and the Nagorno-Karabakh republic on one side and Azerbaijan on the other in May 1994.

Talks on Nagorno-Karabakh have been held on the basis of the so-called Madrid Principles suggested by co-chairs of the Minsk Group of the Organization for Security and Cooperation in Europe (OSCE) - Russia, France and the United States - in December 2007 in the Spanish capital. They include three key principles enshrined in the Helsinki Final Act: refraining from the threat or use of force, territorial integrity and the right to self-determination.