Global leaders rounded on Vladimir Putin on Saturday night as armed separatists continued to block international inspectors attempting to identify and repatriate bodies at the Malaysia Airlines MH17 crash site in eastern Ukraine.

Amid reports that pro-Russia rebels accused of shooting down the plane had removed corpses themselves and were looting credit cards and other possessions belonging to some of the 298 victims, Mark Rutte, the Dutch prime minister, said that Putin had "one last chance to show he means to help [rescuers recover the bodies]".

Rutte vented his anger following what he called a "very intense" conversation with the Russian president. Referring to allegations that bodies of the passengers, including 193 Dutch nationals, were being treated with contempt and allowed to rot at the scene, he said: "I was shocked at the pictures of utterly disrespectful behaviour at this tragic spot. It's revolting."

David Cameron called for the EU and the west to change its approach to Russia if Putin does not alter course on Ukraine following the tragedy. The prime minister said: "This is a direct result of Russia destabilising a sovereign state, violating its territorial integrity, backing thuggish militias, and training and arming them. We must turn this moment of outrage into a moment of action."

Robert Ayley, 28, a father of two, who came from Surrey but lived in New Zealand, was one of those killed. He is pictured with his wife Sharlene. Photograph: PA

Following reports about attempts to use victims' credit cards, Dutch banks said that they were taking "preventive measures" and that any losses suffered by relatives of the dead would be paid back. The DeTelegraaf newspaper said: "The government must make clear to the world that we are beside ourselves with rage."

Speaking about the British government's priorities Philip Hammond, the foreign secretary, said: "Our focus now is on securing the site so there is a proper international investigation to identify the cause and the perpetrators and bring them to justice, and making sure the victims are dealt with with proper dignity and respect."

The US secretary of state, John Kerry, also stressed in a phone call with the Russian foreign minister, Sergei Lavrov, that investigators must get full access to the crash site.

The situation there descended into chaos on Saturday as "experts" of unknown provenance moved bodies decomposing in the baking heat from fields to the roadside, and used bags to collect body parts. A spokesman for the OSCE, Michael Bociurkiw, said: "Some of the body bags are open and the damage to the corpses is very, very bad – it is very difficult to look at."

It was a horrific scene and came despite huge pressure on Moscow to force the rebels to allow proper access to the site. The Ukrainian government accused the separatists of removing 38 bodies from the site to a morgue in rebel-held Donetsk. But as politicians and newspapers across the world lay blame for Thursday's tragedy at the door of pro-Russia separatists and Vladimir Putin personally, the Kremlin has remained defiant. Putin has said Ukraine is to blame, and Russia's defence ministry issued a list of 10 questions for Kiev on Saturday, insinuating that it was a Ukrainian missile that downed the plane, while the self-declared prime minister of the Donetsk People's Republic, Alexander Borodai, told Russian television that the entire event had been a setup by Ukrainian authorities.

"[Ukrainian president Petro] Poroshenko promised a 'surprise' for the rebels. I think this is the surprise he was talking about – a plane full of civilians shot down," said Borodai. However, a senior Ukrainian security official claimed on Saturday that Kiev had evidence the missile was fired from separatist territory by Russian specialists who had crossed the border with the equipment.

The Ukrainian prime minister, Arseniy Yatsenyuk, told a German newspaper that the missile required "very professional staff" and "could not be operated by drunken gorillas", suggesting that the separatists had outside help from Russia. When asked about the growing circumstantial evidence that the separatists shot down the jet in error, thinking it to be a Ukrainian air force plane, Borodai said: "It's a lie and I hope it will be proved as a lie by experts, including international experts who have already arrived on our territory."

However, there were no recognisable international or even Ukrainian experts at the crash site, which was completely controlled by rebel gunmen. Ukraine's government on Saturday accused the rebels of destroying evidence and making life difficult for OSCE observers. "We have to be very careful with our movements because of all the security. We are unarmed civilians, so we are not in a position to argue with people with heavy arms," said Bociurkiw.

Of the 10 dead Britons, the four yet to be identified were named on Saturday as John Allen, a Netherlands-based lawyer who died with his wife Sandra and their sons Christopher, Julian and Ian; Robert Ayley, 28, a dog breeder and father of two from Guildford in Surrey, who lived in New Zealand; Stephen Anderson, 44, who lived in Penang, Malaysia; and Andrew Hoare, 59, a banker who died alongside his Dutch wife Estella and their two children, Friso and Jasper, who were aged 12 and 14 and of Dutch nationality.

Russia's ambassador to the UK, Alexander Yakovenko, has been summoned to the Foreign Office to be told that Putin must use his influence on the separatists to ensure access to the crash site, No 10 said. In Germany, Andreas Schockenhoff, a senior ally of chancellor Angela Merkel, told the Observer: "The disaster in the Ukraine has made it clear beyond all doubt that we are not dealing with a bilateral conflict, but a serious threat to the peace all across Europe."

Schockenhoff said Russia was "not a neutral actor in the conflict" since it had armed and trained the separatists. He called on Europe to show "a united front and make any failure to cooperate very painful for Putin".

Meanwhile, the Russian foreign ministry published a list of 12 US citizens who are now banned from entry to Russia in response to the latest US sanctions. They include officials involved in the running of the Guantánamo detention facility and military personnel involved with the Abu Ghraib prisoner abuse scandal.

Fighting has continued between the Ukrainian army and separatists in east Ukraine since the crash on Thursday, with more than 20 civilians reported to have died in Luhansk on Friday. Ukrainian authorities claimed they had evidence of military equipment transferred to the area from Russia in the early hours of Saturday morning.