Memorial, the acclaimed rights group of Natalya Estemirova, said the pro-Kremlin Chechen president Ramzan Kadyrov was responsible for the murder, irrespective of who ordered the killing.

The corpse of Estemirova, 50, was found Wednesday afternoon with gunshot wounds to the head and chest hours after she was seen being bundled into a car outside her home in the Chechen capital Grozny.

A small funeral ceremony was taking place in the centre of Grozny and she was to be buried in her home village of Ishkhoi-Urt in Chechnya later in the day, Russian news agencies said.

Her murder was just the latest killing of a campaigner in the country, following the 2006 murder of investigative journalist Anna Politkovskaya.

Russian President Dmitry Medvedev — who swiftly condemned the killing — was scheduled to meet German Chancellor Angela Merkel outside Munich for a summit meeting where the murder may be discussed.

"I know, I am sure who is guilty of Natalya Estemirova’s murder, we all know him — his name is Ramzan Kadyrov," said Memorial’s head Oleg Orlov.

Kadyrov had "threatened Natalya, insulted her and considered her a personal enemy."

"We do not know if he gave the order himself or his close associates did so to please their boss," Orlov said.

Kadyrov however voiced outrage over the killing of a "helpless woman" and pledged to oversee the investigation, the RIA Novosti news agency said.

Kadyrov is a hugely controversial figure, praised by the Kremlin for restoring some stability to Chechnya but hated by rights activists who accuse him of allowing a personal militia to carry out kidnappings and torture.

Earlier this month, Memorial and Human Rights Watch issued a hard-hitting report accusing Chechen security forces of punishing families of alleged militants by burning down their homes.

Medvedev "expressed indignation at this murder" and ordered a top-level investigation, Kremlin spokeswoman Natalya Timakova said.

The swift Kremlin reaction — issued just two hours after the murder was confirmed — contrasted with sluggish responses to previous killings of activists such as Politkovskaya.

Russian Deputy Interior Minister Arkady Yedelyev said the prime theory for investigators was the murder was linked to her professional work, the Interfax news agency said.

But he said other theories were being examined and the murder could have been carried out by militant groups or thieves.

"There is also the domestic theory that it was linked to her personal relations and unhappy family relations," he added, without giving further details.

Western states and rights groups urged the authorities to bring those responsible to justice, something Russia failed to do in similar recent cases.

US State Department spokesman Ian Kelly said Washington was "deeply saddened," and added in a statement: "We call upon the Russian government to bring those responsible to justice."

The European Union’s Swedish presidency urged Moscow "to swiftly and thoroughly investigate the murder … and bring the perpetrators to justice."

Kenneth Roth, director of Human Rights Watch, said "it seems to be open season" on activists working to highlight abuses in Chechnya.

Memorial said Estemirova had particularly angered the local authorities by accusing security forces of carrying out an extra-judicial execution of an alleged rebel in public in front of his village on July 7.

Russia earlier this year ended a 10-year "counter-terrorism" operation in Chechnya, a mainly Muslim region riven by two separatist wars since the 1991 collapse of the Soviet Union.

Although she was abducted from close to her home in Chechnya, Estemirova’s body was found in the neighbouring region of Ingushetia which has also been hit by simmering unrest in the last months.

Russia has still failed to solve the murder of Politkovskaya as well as the January killing of young journalist Anastasia Baburova and human rights lawyer Stanislav Markelov who were gunned down in central Moscow.

Stuart Williams/AFP/Expatica