BRUSSELS (Reuters) - NATO accused Russia on Thursday of misleading the alliance over the scope of its war games last month in violation of rules meant to reduce East-West tensions, but Moscow said NATO was stirring up anti-Russian propaganda.

At a meeting with Russia’s ambassador to the U.S.-led alliance, Alexander Grushko, NATO envoys said that Moscow had given conflicting accounts of the exercises known as Zapad, or “West”, in Belarus, the Baltic Sea, western Russia and its Kaliningrad outpost, diplomats said.

NATO ambassadors pressed their message home at a meeting with Grushko at the NATO-Russia Council, a forum that was effectively suspended months after Moscow annexed the Crimean peninsula in March 2014, but now meets regularly again.

Russia’s defense ministry said the war games included some 12,700 troops and ran from Sept. 14 to Sept 20, with a fictional scenario focusing on attacks by militants. NATO says there were far more troops than 12,700 and they simulated an attack on the West during August and September.

Saying they are concerned that large-scale, unannounced exercises could accidentally trigger a conflict in eastern Europe between NATO and Russia, Western allies have pressed Moscow to be clear about its military exercises and to invite more observers.

“The number of troops participating in the exercises significantly exceeded the number announced before the exercise, the scenario was a different one and the geographical scope was larger than previously announced,” NATO Secretary General Jens Stoltenberg told reporters after the meeting.

Under a Cold War-era treaty known as the Vienna document, which sets out rules for exercises, war games that number more than 13,000 troops should be open to observers who can also fly over the drills and allow them to talk to soldiers.

NATO did send one expert to a visitor day in Russia and two experts to a visitor day in Belarus.

NATO diplomats say Moscow massed some 100,000 troops from the Arctic to eastern Ukraine, where Russia backs separatists, and used ballistic missiles and electronic warfare to test its combat capability in Europe.

Grushko said NATO’s assessment was wrong and NATO was wrong to lump all the exercises going on in Russia last month under the Zapad name.

“NATO countries are counting all the military activities that took place in the Russian Federation and counting them as part of Zapad,” he told a news conference after the meeting.

“We don’t accept the propaganda about the Russian exercises,” Grushko said. “It was an unprecedented propaganda attack,” he said.

Some western officials have expressed concern that parts of the Baltic states, which have large ethnic Russian minorities, could be seized by Moscow, much as Russia took control of Ukraine’s Crimea in 2014.

However, Stoltenberg said that Russia had withdrawn its troops from Belarus after the Zapad exercises. Baltic countries had feared Moscow might leave them on NATO’s borders.