Russia is deeply worried by NATO`s pledge to eventually bring Ukraine and Georgia into the alliance, despite its failure to do so immediately, a senior Russian diplomat said Friday, AP reports.

Sergei Ryabkov, chief of the Russian Foreign Ministry`s department for European cooperation, spoke just before Russian President Vladimir Putin sat down for a meeting with NATO leaders on the sidelines of a summit in the Romanian capital.

Ryabkov said Russia`s ties with NATO had soured over what he described as the reluctance by the West to listen to its concerns.

"A culture of searching for solutions on the basis of taking mutual interests into account has been lost," he told reporters.

He criticized NATO`s decision Thursday to promise eventual membership to two of Russia`s ex-Soviet neighbors. NATO failed to offer the two nations specific membership plans because Germany, France and some other alliance members feared the move would anger Russia.

NATO Secretary-General Jaap de Hoop Scheffer reassured Ukraine and Georgia Friday that there was "not a sliver of a doubt" the two ex-Soviet republics would join the alliance before long.

He also told reporters at the NATO summit in Bucharest that the Western military alliance will help Ukraine in any way it can to make reforms.

"These countries will become members of NATO — there can be no misunderstanding about that," de Hoop Scheffer said.

Ukrainian President Viktor Yushchenko said his country understands the challenges that delayed its bid and remains devoted to democratic and European values.

"I`m not a naive politician, and I clearly understand what debates and challenges we were speaking about," Yushchenko said. He also said he was confident that Ukraine would get a formal "membership action plan" at a December meeting of NATO foreign ministers.

But Ryabkov said that NATO`s firm pledge to grant membership to Ukraine and Georgia infringed on the rights of their citizens.

"The allies have taken this decision without asking the population," he said.

Ukraine is divided between western regions that support the NATO bid and Russian-speaking eastern and southern provinces that staunchly oppose it.

In Georgia, the majority of citizens supported the NATO bid in a recent referendum. But that nation is plagued by conflicts in the separatist provinces of Abkhazia and South Ossetia, which have close ties with Russia.

Putin has vowed to broaden Russian support for the regions and warned Georgia and the West against the use of force or pressure to bring them back under central government control, the Russian Foreign Ministry said Thursday.

It said Putin`s pledge came in response to messages from the leaders of Abkhazia and South Ossetia expressing concern about Georgia`s NATO drive.

Putin, however, stopped far short of saying Russia would recognize the independence of Abkhazia and South Ossetia — a move that would severely damage ties with the West and could spark a war with Georgia. He gave no indication that Russia would abandon its official acceptance of Georgia`s territorial integrity.

Ryabkov also voiced a strong concern about NATO`s support for the U.S. plan to deploy missile defense sites in Poland and the Czech Republic.

The NATO statement called on its members to explore ways in which the planned U.S. shield can be linked with future missile defenses elsewhere. It said leaders should come up with recommendations to be considered at their next meeting in 2009.

"We have new concerns about plans to integrate U.S. missile defense plans with NATO system," he said, signaling that Russia may abandon cooperation with NATO on a short-range missile defense in Europe.

"We can`t sit aside and watch how they rubber-stamp decisions made by other people changing the security situation for Russia," Ryabkov said, referring to Washington`s missile defense plan.

Putin views the U.S. missile shield as a threat to Russia`s nuclear deterrent and has shrugged aside U.S. pledges that it is intended to counter a missile threat from Iran. He and Bush are set to discuss the issue at their meeting in Putin`s Black Sea residence in Sochi this weekend.

Ryabkov said that, despite sharp differences, Russia stands ready to cooperate with the alliance on issues where their interests converge, such as Afghanistan.

Russia has agreed to a transit deal with NATO to allow the alliance to ship non-lethal freight across Russian territory to military forces in Afghanistan, he said.