Hollebaek sounded a warning note on his visit to the country on Thursday, which followed a series of incidents in the southwest.
Trouble started in late January at a village carnival where local Macedonians wore masks deemed highly offensive to Muslim Albanians.
Later a church was almost burned in the ethnically mixed town of Struga and a Macedonian flag was torched.
“I see an increased tendency with regards to separation along ethnic lines”, Vollebaek warned. “All of this can potentially represent a threat to social cohesion.”
Macedonia should not wait for incidents to happen to address the issue, he said. “Education is highly relevant in preventing incidents from escalating,” he added.
Vollebaek said the country must step up efforts to bring children from different backgrounds together, a model that few schools apply today.
On the initiative of the OSCE and local NGOs, a mere five schools - four primary and one high school – organize classes uniting children from the Macedonian, Albanian, Turkish and other communities.
The OSCE is pushing for a wider implementation of this practice, which they say is crucial in a post-conflict society like Macedonia.
In 2001 Macedonia suffered a short-lived armed conflict between the Macedonian security forces and ethnic Albanian rebels. The hostilities ended with the signing of a peace deal that same year that granted greater rights to the country’s Albanians.
Albanian Muslims make up about a quarter of the population of 2.1 million.
As part of his visit Vollebaek met President Gjorge Ivanov, Prime Minister Nikola Gruevski as well as with political party and religious leaders.