.MOSCOW (AP) – President Vladimir Putin warned Tuesday against political ideas that are “placed above basic values” as he for the first time joined public commemorations on the 70th anniversary of mass killings ordered by Soviet dictator Josef Stalin.

Putin’s presence at the Butovo firing range, where some 20,000 priests, artists and other “enemies of the people” were executed in 1937-38, was a noteworthy gesture by the former KGB officer, who has restored Soviet-era symbols and tried to soften public perceptions of Stalin.

Rights activists, however, said the visit to mourn victims of the “Great Purge” was an election ploy and warned that the consolidation of power that has occurred under Putin risks returning Russia to the repression of the communist era.

Putin joined the head of the Russian Orthodox Church for a ceremony at the recently built Church of New Martyrs and Confessors and laid red roses at a 40-foot wooden cross carved at a monastery on the White Sea’s Solovki Islands. The islands were home to one of the earliest and most notorious labor camps in the Soviets’ gulag network.

The two then strolled through the fog-shrouded birches and dampened grass growing among long earthen mounds that hold Butovo’s mass graves. The field was used for executions from the 1930s until Stalin died in 1953.

Later, Putin looked at a paneled explanation of the site, complete with a day-by-day tally of the killings and photographs of gaunt and haggard victims.

“These tragedies have occurred in history not just once. And they always occurred when ideals that seemed attractive at first glance but then turned out to be empty were placed above basic values: human life, rights and freedom. For us, this was a particular tragedy because its scope was colossal,” Putin told reporters.

Putin also appeared to warn politicians and political activists about how to conduct themselves in the run-up to parliamentary elections in December and the presidential vote in March.

“Of course political battles and political arguments and the battle of opinions is necessary, but we need for that process not to be destructive, for it to be constructive,” he said. “Political battles should take place in a cultural and educational context.”

Putin’s visit was significant since his government had largely ignored the 70th anniversary all year, even as the Orthodox Church held a series of ceremonies to commemorate “martyrs” – priests executed by the Soviet police – and other victims.

The president has tried to soften public perceptions of Stalin as part of an effort to restore Russians’ pride in their Soviet-era history. In June, he told history teachers that although the 1937 mass slaughter was one of the most notorious episodes of the Stalin era, no one should try to make Russia feel guilty about it because “in other countries even worse things happened.”

Lyudmila Alexeyeva, a Soviet-era dissident who heads the Moscow Helsinki Group, said on Ekho Moskvy radio that Putin’s visit to Butovo was obviously part of the election campaign. She said his government now holds some 100 political prisoners who she charged were jailed on fabricated charges of espionage and terrorism and about 30 more targeted for actual political activity.

Valeria Dunayeva, from Memorial, a group dedicated to investigating Stalin’s abuses, said Russia is threatened with “an imminent return” to its old ways. “Without comprehending the past there can be no future,” she said.

Sergei Volkov, head of the Association of Victims of Political Repression, also warned of the danger of new repression.

“It’s the fault of the man who has stepped with one foot into democracy and still stands with another in KGB – our president, Vladimir Putin,” Volkov said.