MOSCOW, February 18 (RIA Novosti) - Russia regards threats by the Ukrainian authorities to expel its ambassador as another attempt to damage bilateral ties, the Foreign Ministry said in a statement on Wednesday.

Ukraine warned Viktor Chernomyrdin on Tuesday that he could be expelled from the country over "unfriendly and extremely undiplomatic assessments, comments and statements regarding Ukraine and its leadership."

"It is amazing how consistent the Ukrainian Foreign Ministry has been in its attempts to damage Russian-Ukrainian cooperation," the ministry said.

A Russian deputy foreign minister said Ukraine's threats to declare Chernomyrdin persona non grata were "outrageous" and "inadmissible."

"I'm ashamed for the Ukrainian leadership, which has stooped to making such demarches at such a high level. This ill becomes our neighbors," Grigory Karasin said.

Calling Chernomyrdin a "respectable politician," he said "there are diplomatic instruments for making one's opinion known to the leadership of other countries without resorting to such actions."

Ukrainian Foreign Minister Volodymyr Ohryzko accused Chernomyrdin of violating diplomatic ethics and international law, including the Vienna Convention on Diplomatic Relations. He said Russia's general consuls in Kharkov and Odessa and some Russian Embassy officials had also violated the convention.

Chernomyrdin, formerly a longtime Gazprom chief, is known to have criticized Ukraine in its bitter gas dispute with Russia in January which led to a cutoff in supplies to the EU as Moscow accused Kiev of tapping Europe-bound transit gas.

In a January 18 interview with Russia's Vesti TV channel, in particular, he described the situation with gas transits as "nonsense" and "buffoonery," and said that "everything proceeds from Ukraine's leadership."

"Either they are unaware of what they are doing, or they are aware but doing it on purpose," he said.

The Foreign Ministry said: "Activities by Ambassador Chernomyrdin and other Russian representatives in Ukraine are aimed at creating favorable conditions for the development of bilateral relations in line with the Russian and Ukrainian peoples' genuine interests."

Relations between the two former Soviet neighbors have been strained over a host of issues, including energy prices and Ukraine's pro-Western policies.