U.N. deputy spokesman Eduardo del Buey would not say whether the missing person was a military or civilian member of the international or local staff.
"We can confirm that a staff member is not accounted for and we are in touch with the relevant parties to determine what has happened," del Buey said. "We have no further comment at this time."
Austria, Croatia, India, Japan and Philippines are currently contributing military personnel to the U.N. Disengagement Observer Force, known as UNDOF, according to the website of the U.N. Peacekeeping Department. It does not list the nationalities of civilian staff. The total force is comprised of around 1,150 people.
The U.N. force was established in 1974 following the 1973 Yom Kippur war to monitor the disengagement of Israeli and Syrian forces and maintain the cease-fire. Israel captured the Golan Heights from Syria in 1967 and Syria wants the land returned in exchange for peace.
U.N. Secretary-General Ban Ki-moon has warned of escalating military activity along the Israeli-Syrian border as a result of the intensifying Syrian conflict, which has gone on for two years and cost more than 70,000 lives.
In December, Ban accused the Syrian government of serious violations of the 1974 separation agreement and called on both countries to halt firing across the cease-fire line. He also cited numerous clashes between Syrian security forces and opposition fighters in the disengagement zone.
In response, he said, UNDOF has adopted a number of security measures.