The Open Skies treaty allows its 34 full members across Europe, Canada and the former Soviet Union to carry out unarmed surveillance flights over other member countries at short notice.

But US President Donald Trump announced on Thursday he planned to pull out of the accord, the latest in a series of US withdrawals from major international agreements.

Washington accused Russia of failing to follow the treaty's rules by blocking flights -- claims denied by Moscow.

Deputy Foreign Minister Sergei Ryabkov said Washington has put forth unacceptable demands for Moscow to meet or it will pull out in six months.

"The conditions the US has presented are absolutely unacceptable... they are senseless, they are unfounded," Ryabkov told a press conference, though adding that Russia is ready to "continue dialogue".

He said Trump's announcement was a "surprise" and accused Washington of "sowing discord and uncertainty among its own allies."

The only thing the US wants, he said, is "for us to stand at attention and then march in the direction they point."

Deputy Foreign Minister Alexander Grushko promised Russia would continue to honour its commitments.

"As long as the treaty is in force, we intend to fully follow all the rights and obligations that apply to us from this treaty," he told RIA Novosti news agency.

The treaty, which was signed in 1992 and came into force in 2002, is seen as an important tool to prevent conflicts by allowing nations to monitor weapon build-ups.

Grushko said Russia was "acting on the basis that all the other countries will act in the same way" and "take a conscientious approach to the obligations of parties to this treaty".

The Russian diplomat said the US pullout would damage European security and harm the interests of US allies.

China, which is not a party to the treaty, expressed "deep regret" over the US move, calling it a "display of the United States' entrenched Cold War mentality".

The withdrawal "will have a negative impact on the international arms control and disarmament process," foreign ministry spokesman Zhao Lijian said at a regular press briefing in Beijing on Friday.