Saint Petersburg (AFP) - In wooded northern Russia, near the Finnish border, archaeological digs by a patriotic historical group are unearthing controversy.

The Russian Military History Society, which was created by the Kremlin, says it is seeking the remains of Soviet soldiers who died when the region was occupied by Nazi-aligned Finns during World War II.

But human rights activists allege the organisation is trying to cover up Stalin-era repressions in the Sandarmokh forest, in Karelia.

The forest is known as the place where as many as 9,000 people were executed during Joseph Stalin's purges.

"The search for the remains of soldiers from the Second World War on the site of mass executions by the NKVD (the predecessor of the KGB, now the FSB) in the 1930s looks like an attempt to manipulate memory," the Memorial rights NGO said on its website.

It accused the history society of seeking to "hide the victims of the terror behind other victims".

It is "unlikely" that Finns executed Soviet prisoners of war in Sandarmorkh, Memorial said.

However the Russian Military History Society said it had found the remains of five people, apparently Soviet soldiers, during digs in late August and early September.

"A body was found in an individual grave... with hands tied behind the back and the remains of a bullet in the skull. It is clear this person was executed," said society scientific director Mikhail Miagkov during a press conference.

Further tests were being carried out, he said.

According to historian Sergei Verigin, who works with the military society, Finnish troops used camps built by the NKVD to hold thousands of Soviet prisoners in the Sandarmokh region.

"Finnish historians have only studied the executions of Soviet prisoners in Finland, but not on Russian territory," he said.

Russia in recent years has seen an official trend to present Stalin's rule in a positive light, while downplaying the repressions and forced collectivisation that killed millions.

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- Echoes of Katyn massacre -

Rights groups remain convinced these digs have a political element.

"For me, it's clear the aim of these digs is to manipulate public opinion, it's an attempt to cover up Stalinist crimes," Anatoly Razumov, a historian who specialises in the purges, told AFP.

Razumov pointed to the 2016 arrest of his colleague Yury Dmitriyev, who researched Stalin-era mass graves in the region.

Authorities launched a highly controversial sexual abuse probe against Dmitriyev, the head of Memorial's branch in Karelia.

He was acquitted in April this year but then the local supreme court annulled the judgement and brought new charges.

"I fear they want to do with Sandarmokh what they did with Katyn," said Razumov, referring to a forest near the Russian city of Smolensk where around 25,000 Polish soldiers were shot and buried in 1940 on Stalin's orders.

Up to 1990, the USSR insisted the massacre was carried out by the Nazis.

"To my mind the case against Yury (Dmitriyev) is a link in the same chain," the historian said.

In early August, Russian opposition party Yabloko and relatives of those executed in the Stalinist purges filed a case in a local court against the digs.

They said they were illegal because they were taking place on a site of historical memory.

"The digs carried out by the Russian Military History Society did not touch the mass graves of repression victims," spokeswoman Nadezhda Usmanova told AFP.

"Soviet soldiers who died during the war also deserve to be found and buried. One truth does not replace another," she said.