The presidents of arch-foes Armenia and Azerbaijan agreed Tuesday to discuss a peace settlement over the disputed region of Nagorny Karabakh, the European security body OSCE said.

"The presidents agreed to advance negotiations toward a peaceful settlement... They agreed to meet again in the months ahead," the OSCE said in a statement after the two leaders met in Vienna.

The presidents of arch-foes Armenia and Azerbaijan will meet in Vienna Tuesday for the first time in two years in a bid to restart stalled negotiations over the disputed region of Nagorny Karabakh, mediators said.

Armenia's Serzh Sarkisian and Azerbaijan's Ilham Aliyev will meet along with mediators from the Organisation for the Security and Co-operation in Europe's (OSCE) Minsk Group, which has been spearheading attempts to negotiate a solution to the conflict.

Azerbaijani strongman leader Ilham Aliyev has replaced his long-standing defense minister in a surprise move announced during the unveiling of new a cabinet following his crushing presidential election win.

Aliyev ditched Safar Abiyev, who has held the post since the mid-1990s, late Tuesday in favour of interior troop commander Zakir Gasanov.

Azerbaijani forces on Tuesday killed an Armenian soldier and injured three more along the volatile border between the two arch-enemies, the Armenian government said.

Garik Pogosyan, 19, was killed when the convoy he was in came under fire on a road that runs along the border, the defense ministry said in a statement.

Azerbaijan on Wednesday accused Armenia of resettling Syrian refugees in a disputed territory the two have been fighting over for decades.

Azerbaijan's U.N. ambassador said the rival neighbor had started a "very dangerous process with unpredictable consequences" by moving Syrian Armenians into Nagorny Karabakh.

At least five Armenian civil society activists have been attacked by unidentified assailants while taking part in recent protests in the capital Yerevan, Human Rights Watch said on Thursday.

"A spate of violent attacks against peaceful protesters appears to be a concerted effort to intimidate activists and should be effectively investigated," the New York-based rights group said in a statement.

Azerbaijani troops shot dead one Armenian soldier and wounded another along the volatile border between the two countries, the defense ministry in Yerevan said on Friday.

Private Norair Petrosyan was killed in the incident on Armenia's south-western border with the autonomous Azerbaijani exclave of Nakhichevan, said defense ministry spokesman Artsrun Hovannisyan.

Turkey on Thursday accused neighboring Armenia of using "disproportionate force" after a shepherd was shot dead by Armenian soldiers patrolling the sealed border, local media reported.

Governor Eyup Tepe said there had been similar incidents in the past and chided Yerevan for using "disproportionate force," in remarks carried by the private Dogan News Agency.

Turkish Armenians are on edge after weekend attacks against members of the community during Orthodox Easter raised fears about their security.

An unidentified assailant fired seven blank rounds outside an Armenian church in Istanbul's Kumkapi neighborhood on Sunday, causing panic among people celebrating Easter there, the Hurriyet newspaper reported.

They dropped their language and religion to survive after the 1915 genocide, but close to 100 years on Turkey's "hidden Armenians" want to take pride in their identity.

Some genocide survivors adopted Islam and blended in with the Kurds in eastern Turkey's Dersim mountains to avoid further persecution.