Pinchuk urged the government in Kiev to offer more realistic proposals on EU membership, Crimea and Donbass to "move toward a solution for a free, united, peaceful and secure Ukraine," in an op-ed published last month in the Wall Street Journal.
"I agree with his noble appeal for peace in Donbass [eastern Ukraine] but cannot agree with the appeal for compromises based on worries," Kostyantyn Yelisieiev, deputy head of Poroshenko’s administration, replied in an article published on the presidential website on Thursday.
The Ukrainian government launched an operation in eastern Ukraine to defeat pro-independence militias in April 2014, a month after almost 97 percent of Crimea’s population voted in a referendum to reunite with Russia, prompting sanctions from the United States and its allies, who called it an annexation.