“It’s extremely high, at any moment,” Denis Pushilin told journalists in response to a possible escalation in the crisis.
The negotiator added that conflicting sides must first "understand how the Minsk II agreement is working," before starting any new peace negotiations.
On Thursday, Russian Foreign Minister Sergei Lavrov called for a fresh round of talks on Ukraine in the four-party Normandy Format, which also includes Germany and France.
Last month, Kiev and the Luhansk and Donetsk People's Republic signed a ceasefire deal in the Belarusian capital to try to end the almost year-long hostilities, which have killed over 6,000 people, according to UN estimates.
Pushilin also urged both sides of the conflict "not to get carried away by emotion" but wait for the UN Security Council (UNSC) to give their evaluation of how the Minsk II deal is being followed.
On Thursday, Russia's envoy to the United Nations Vitaly Churkin said that Russia has submitted a draft resolution on the implementation of the Minsk II Accords to the UNSC.
The Minsk II agreement is a 13-point deal, envisioning a ceasefire, the pullout of heavy weapons and an all-for-all prisoner exchange, as well as granting special status to the breakaway republics.
