DONETSK: A train carrying the remains of many of the nearly 300 victims of the Malaysia Airlines plane downed over Ukraine arrived in Ukrainian government territory on Tuesday as a separatist leader handed over the plane’s black boxes to Malaysian experts.

The train carrying around 200 body bags arrived in the eastern city of Kharkiv, which is in Ukrainian government hands. The bodies will then be taken back to the Netherlands to be identified.

The train left the crash site after the Malaysian prime minister agreed with the separatists for recovered bodies to be handed over to authorities in the Netherlands, where two thirds of the victims came from.

The handover and reports by international investigators of improved access to the wreckage of the airliner four days after it was shot down, came amid calls for broader sanctions against Russia for its support for the rebellion, although Western leaders are struggling to agree on a response.

The first bodies from the MH17 crash in Ukraine will be flown on Wednesday to the Netherlands, where their identification could take months, Prime Minister Mark Rutte said.

“Tomorrow the first plane (with bodies) will leave for Eindhoven” in the southern Netherlands, Rutte told journalists after the bodies arrived in Ukraine’s Kharkiv town from rebel-held territory.

“Preparations will be made in Kharkiv so that identification can be done in the Netherlands as well as possible,” Rutte said.

“As soon as a victim is identified, first and foremost the family will be informed and no one else. That can take weeks or months.” Early on Tuesday, senior separatist leader Aleksander Borodai handed over the black boxes in the city of Donetsk.

“Here they are, the black boxes,” Borodai told journalists at the headquarters of his self-proclaimed Donetsk People’s Republic as an armed rebel placed the boxes on a desk.

Col. Mohamed Sakri of the Malaysian National Security Council said the two black boxes were “in good condition.”

Shaken by the deaths of 298 people from around the world, Western governments have threatened Russia with stiffer penalties for what they say is its backing of pro-Russian militia who, their evidence suggests, shot the plane down.

At the United Nations, the Security Council unanimously adopted a resolution demanding those responsible “be held to account and that all states cooperate fully with efforts to establish accountability.”

It also demanded that armed groups allow “safe, secure, full and unrestricted access” to the crash site.

“We owe it to the victims and their families to determine what happened and who was responsible,” said Australian Foreign Minister Julie Bishop. Australia lost 28 citizens in the crash.

Malaysian Prime Minister Najib Razak announced shortly after midnight that his government had negotiated the release of the remains of nearly 300 victims of Flight MH17 from separatist-held territory.

Najib, working through intermediaries to reach rebel leader Alexander Borodai, was a key figure in brokering the deal, according to two sources in Malaysia with direct knowledge of the negotiations.

The talks were kept under tight wraps, with Najib initiating the conversation and bringing only a handful of his closest confidants into the discussions.

“It was the Prime Minister’s project,” one of the sources said.

President Vladimir Putin said on Tuesday Russia would use its influence with separatists in east Ukraine to allow a full investigation into the downing of a Malaysian airliner, but said the West must put pressure on Kiev to end hostilities.

Putin also called on Western powers not to meddle in Russia’s domestic affairs and said steps were needed to strengthen the country’s military capabilities because of moves by NATO and to protect the economy from “external threats.”