The OSCE's chairman in office is in Armenia, the last stop in his tour of the South Caucasus.
Didier Burkhalter, who is also the Swiss foreign minister, arrived in Yerevan from the Georgian capital, Tbilisi, on June 3.
Accompanied by Armenian Foreign Minister Eduard Nalbandian and Yerevan Mayor Taron Margarian, Burkhalter took part in a tree-planting ceremony at the Armenian Genocide Memorial on June 4.
Burkhalter is due to hold talks with Armenian President Serzh Sarkisian and other top officials to discuss Armenia-EU ties and the situation regarding the disputed territory of Nagorno-Karabakh.
Burkhalter's tour of the region began on June 2 with a visit to the Azerbaijani capital, Baku.
In Baku and Tbilisi, Burkhalter discussed issues related to regional security and ties between the EU and the Caucasus states.
With reporting by news.am