"The date has not yet been determined, experts are drafting documents. It should definitely be held before June 30 because we do not yet have a decision on the third quarter," Novak said.
The future of Russian gas deliveries to Ukraine this fall amid its unsettled multi-billion dollar debt to Russia is expected to be at the center of talks under the European Commission's mediation.
On April 1, the two countries' gas companies signed a supplementary agreement extending Russian gas deliveries to Ukraine for the second quarter of 2015, due to expire by the end of next month.
Further extension of Moscow's $100-per-1,000-cubic meters discount has come under doubt following the Ukrainian Parliament's law passed earlier this week which, if ratified by President Petro Poroshenko, would suspend Kiev's foreign debt payments.