KIEV, August 13 (RIA Novosti) - Ukrainian President Viktor Yushchenko said he was very disappointed by the Russian leader's recent open letter to him, describing the message as "unfriendly."

President Dmitry Medvedev accused Yushchenko in an open letter on Tuesday of pursing anti-Russian policies.

Medvedev expressed his "deep concern at the current, without exaggeration, crisis in Russian-Ukrainian relations," and said he would not send the new ambassador to Kiev for the time being.

"To be frank, I am very disappointed by [the letter's] unfriendly nature," Yushchenko said responding to the message. "I agree that relations between our countries face major problems, but I find it strange that you totally rule out any responsibility for them on Russia's side."

Yushchenko said Moscow's decision to delay its new ambassador's arrival to Ukraine would not help cooperation between the two countries.

He again dismissed Russian claims that Kiev supplied military aid to Georgia, with which Russia fought a brief war last August, saying any arms delivered to the Caucasus state were in compliance with international law.

Yushchenko also urged Moscow to respect Ukraine's right to join NATO.

Ukraine's NATO bid has marred relations between Moscow and Kiev. The two countries also had a series of bitter gas disputes affecting supplies to Europe.