Malaysia issued an impassioned plea Saturday for the MH17 disaster site in Ukraine to be protected from tampering, saying evidence was being compromised in what it called a "betrayal of the lives that were lost."

Concerns are mounting over the integrity of the crash zone in rebel-held eastern Ukraine, with the government in Kiev on Saturday accusing Moscow of helping pro-Russian separatist insurgents destroy evidence.

The Foreign Ministry denied on Saturday reports saying that two Lebanese nationals, holding the Australian citizenship, were among the 298 people on board the Malaysian jetliner that crashed in violence-wracked Ukraine.

“After the Foreign Ministry obtained the detailed name list of the passengers on the flight and after contacting our the Lebanese Embassy and Consulate in Australia, we found out that the two individuals are not Lebanese,” the ministry said in a statement.

Ukraine on Saturday accused Russia of helping separatist insurgents they say shot down Malaysian airliner MH17 try to destroy evidence at the crash site. 

"The Ukrainian government officially announces: terrorists with the support of Russia are trying to destroy proof of this international crime," Ukraine's government said in a statement.

Prime Minister Najib Razak's step-grandmother was on board the Malaysia Airlines passenger jet that crashed in violence-wracked Ukraine, the country's defense minister confirmed Saturday.

Hishammuddin Hussein, a cousin of Najib's, said 83-year-old Sri Siti Amirah was "on the flight". Siti Amirah was also Hishammuddin's step-grandmother.

Dutch Prime Minister Mark Rutte on Friday vowed "not to rest" in tracking down those responsible for downing Malaysia Airlines flight MH17 if it emerges it was attacked, as Malaysia's premier demanded that the possible perpetrators be brought to justice.

The Netherlands has dispatched Foreign Minister Frans Timmermans and a team of forensic experts to Ukraine to probe the disaster, in which 189 Dutch citizens died.

A London-based reporter for Russia's state-owned English-language channel RT quit Friday in protest at its coverage of the Malaysia Airlines crash in Ukraine.

Sara Firth is the second person since March to publicly resign from RT, formerly known as Russia Today, over its coverage of the Ukraine crisis.

German Chancellor Angela Merkel called Friday for an immediate ceasefire in Ukraine to facilitate a probe into the apparent downing of a passenger plane in the rebel-held east of the country.

Merkel said Russia in particular must do its part to bring about a "political solution" to the conflict in Ukraine, adding that Moscow bore responsibility "for what is happening" in the strife-torn country.

U.S. President Barack Obama hinted Friday that a Malaysian passenger plane flying over eastern Ukraine was shot down by pro-Moscow separatists, as the U.N. Security Council demanded a full, independent and international probe into the deadly incident.

At a press conference, Obama said a missile fired from rebel-held territory in Ukraine downed the Malaysian jet as he pressed for an international investigation.

An initial review of U.S. intelligence suggests pro-Russian separatists likely shot down a Malaysian airliner over Ukraine, but Washington is still examining the evidence, a U.S. official said Friday.

"There are indications (the separatists downed the plane) but there's no final conclusion," the U.S. official, who spoke on condition of anonymity, told Agence France-Presse.

Fidel Castro accused Ukraine on Friday of shooting down the Malaysia Airlines plane that crashed in rebel-held territory, blaming its "pro-imperialist" government for the disaster that killed 298 people.

"Cuba... must express its repudiation of this action by such an anti-Russian, anti-Ukrainian and pro-imperialist government," the 87-year-old father of the Cuban Revolution wrote in the official newspaper Granma.