Ukraine's U.N. ambassador said Thursday he is "completely outraged" by Secretary-General Ban Ki-moon's comments in a speech saying Russia has a critical role to play in ending the conflict in his country.

Volodymyr Yelchenko said said Ban's prepared comments for the St. Petersburg International Economic Forum in Russia show he has lost "any moral right" to say anything about the conflict in Ukraine.

He said he doesn't understand how the U.N. chief "can say such things which sort of praise the role of Russia in settling the conflict in Ukraine when the Russian Federation is the main player in aggressing Ukraine and in keeping this conflict boiling."

Yelchenko said Ukraine is sending a protest letter to the 193-member General Assembly asking for a correction and explanation.

U.N. spokesman Stephane Dujarric said "we're not going to walk back from what we said." He urged everyone to read the entire speech, but said "I'm not going to analyze or respond to criticisms that may have been received."

Fighting in eastern Ukraine broke out in April 2014 after Ukraine's Russia-friendly president was ousted following months of street protests and Russia annexed Crimea -- a move that led to crippling Western sanctions on Russia.

A February 2015 agreement has helped reduce fighting between pro-Russian separatists and Ukrainian forces, but frequent clashes have erupted and efforts to reach a political settlement have stalled.

In his prepared speech circulated by the United Nations, Ban said Russia as a veto-wielding permanent member of the U.N. Security Council has "a critical role to play" in addressing "pressing global issues, from ending the conflicts in Ukraine and Syria, to safeguarding human rights and  controlling the proliferation of weapons of mass destruction."

Yelchenko criticized Russia's crackdown on human rights in Crimea and said Ukraine has circulated "a number of letters describing how the Russian Federation is building up the nuclear potential in Crimea."