The Chechen leader Ramzan Kadyrov’s anger over the loss of his Instagram account due to US sanctions probably led to ongoing attacks against Russia’s oldest human rights organisation, members of the group have said.

Memorial – the only human rights organisation with a presence in Chechnya – last week had its offices in the southern Russian republic of Ingushetia torched by masked men. The attack came days after Oyub Titiev, the head of Memorial’s office in Grozny, the Chechen capital, was arrested for possession of six ounces of cannabis, charges that could bring a 10-year prison sentence.

The group believes Chechen security forces were involved in both cases and were acting in revenge for the closing down of Kadyrov’s Instagram account. He had been regularly posting content to his more than 3 million followers ranging from barely-veiled threats against Kremlin critics to photographs of himself cuddling or wrestling exotic animals. The Chechen deputy interior minister, Apti Alaudinov, has previously encouraged police officers to frame people by planting incriminating evidence.

“The closure of his Instagram account is a matter of Kadyrov’s image, of his prestige. When he feels offended, nothing else is important to him – whoever gets in his way must be destroyed,” said Oleg Orlov, a Memorial founder.

“We were held responsible for this by Kadyrov and his inner circle because we are one of the very few sources of information about rights abuses in Chechnya.”

Kadyrov, 41, a former separatist fighter who is now a staunch ally of Vladimir Putin, was sanctioned in December by the US Treasury over alleged human rights abuses, including involvement in extrajudicial killings. Facebook, which also owns Instagram, said the US decision meant it was legally obliged to deactivate his accounts.

Magomed Daudov, the speaker of the Chechen parliament, has previously blamed human rights activists for the US sanctions and the blocking of Kadyrov’s social media accounts, calling them “enemies of the people”. Kadyrov last week said the activists had “no clan, no nation, no religion” and vowed he would not allow them to operate in Chechnya.

“I think this is partly revenge for losing his Instagram [account],” said Katya Sokirianskaia, a Memorial member who formerly headed the organisation’s office in Grozny. “Being placed on the US sanctions list didn’t really bother Kadyrov, but the loss of Instagram was very painful for him. Kadyrov loved his Instagram. It was a very powerful propaganda tool for him, not just his favourite toy.”

Memorial, which was founded in 1989 by Soviet dissidents, has gained international respect for its work on both Soviet-era repression and modern-day human rights abuses. Most recently, it helped document a crackdown against gay men in Chechnya, and verified the names of over a dozen people allegedly executed by Chechen security forces last January. But it fears being driven out of the mainly Muslim republic.

“Memorial is not only Russia’s leading rights group but also the country’s key organisation exposing abuses in the turbulent North Caucasus and providing legal aid and other assistance to the victims,” said Tanya Lokshina, a senior Moscow-based researcher at Human Rights Watch. “If Chechen authorities now succeed in pushing Memorial out of Chechnya, victims of the most horrific abuse will have nowhere to turn.”

The group was censured in 2015 under the Russian government’s “foreign agent” law, adding layers of bureaucratic complications to its operations, while last year Yury Dmitriyev, the head of its office in Karelia in northern Russia was arrested on child pornography charges. Dmitriyev denied the charges, which critics said were revenge for his uncovering of mass executions by Joseph Stalin’s secret police.

A judge unexpectedly ruled last month that he be freed from pre-trial custody, but he was quickly transferred to a psychiatric hospital in Moscow for tests.

It is in Chechnya that the group has suffered most. In 2009, Natalia Estemirova, a Memorial board member, was abducted in Grozny, the Chechen capital, and shot dead. Her bullet-riddled body was later found in Ingushetia. No one has been charged with her murder.

Memorial members initially feared that a similar fate had befallen Titiev after he was seized by police last week. The US state department and the Council of Europe have both urged the Chechen authorities to release Titiev, while even the Kremlin’s human rights council said it did not exclude the possibility that drugs had been planted on the Memorial activist by Chechen police.

Titiev wrote a letter to Putin this week saying that should he admit to the charges against him, it would mean he had been tortured or blackmailed into doing so. “Our work in Grozny is paralysed,” said Alexander Cherkasov, the Memorial chairman. “We have never before had one of our colleagues effectively taken hostage.”