An American monitor with the Organization for Security and Cooperation in Europe (OSCE) died and several other monitors were injured Sunday when their car hit a mine near Luhansk in eastern Ukraine.
Austria's foreign ministry confirmed the incident near the small village of Pryshyb.Austria currently holds the OSCE’s rotating presidency.
Austrian Foreign Minister Sebastian Kurz demanded a thorough investigation, adding that those responsible would be held accountable.
A German and a Czech national were also injured but have been treated at a local hospital.
According to reports, the vehicle drove over a mine in territory controlled by the self-proclaimed Luhansk People's Republic.
The chief of the OSCE Special Monitoring Mission (SMM), Ertugrul Apakan, said he is travelling to Luhansk Monday to extend his support to the monitors and to better understand the situation.
In a statement, Apakan said the OSCE remains committed to fulfilling its mandate and contributing to bring peace to the people of Ukraine.
A rebel statement said the OSCE team was traveling along an unsafe road."We know that the mentioned crew deviated from the main route and moved along side roads, which is prohibited by the mandate of the OSCE SMM," local media reported.
The incident marks the first loss of life for the OSCE's Special Monitoring Mission to Ukraine.
The OSCE has 600 members in eastern Ukraine, and is the only independent monitoring mission in the destroyed industrial war zone.It provides daily reports on the war and has angered insurgents for accusing them of being responsible for most truce agreement violations.
During the past three years tensions between Ukraine and separatists in the Russian-held eastern part of the country have continued to increase.A 2015 cease-fire agreement is repeatedly violated.
At least 9,750 people have been killed in the war in eastern Ukraine since April 2014.More than 40 died during the first two months of this year, when hostilities suddenly surged.