Malaysia Airlines crash: Who shot down the plane?

CTV National News: Calls for justice and answers Joy Malbon reports on calls for an independent investigation of Flight MH17 with concerns evidence has been tampered with.

A Malaysia Airlines passenger plane carrying 298 people crashed in eastern Ukraine, between Donetsk and the border with Russia, where pro-Russian rebels have been fighting with government forces in the region for months.

On several verified and unverified images and videos, thick black smoke can be seen billowing in the distance. Malaysia's Prime Minister tweeted that his government will launch an investigation, as rumours started circulating that the plane had been shot down.

The Ukrainian government and the pro-Russian rebel forces in the region immediately blamed each other. Anton Herashenko, an adviser to Ukraine's interior minister, wrote on Facebook that a BUK surface-to-air missile system shot down the plane. The BUK launcher is Russian made and can engage targets flying well above the altitude of MH17. Herashenko didn't reveal how he learned about the information. He also wrote on Facebook that he saw reports of a BUK system being moved from Torez Thursday morning. The Associated Press reported journalists for their outlet saw a similar launcher in the area earlier Thursday.

Rebel spokesmen in Donetsk denied it was them and told The Associated Press it must have been Ukrainian government troops. Andrei Purgin, deputy prime minister for the rebels, did not give any proof. According to Russia's Interfax news agency, Serhiy Kavtaradze, a member of the rebels' security council said "The plane was shot down by the Ukrainian side…We simply do not have such air defence systems."

Kavtaradze continued to say the rebels only have shoulder-launched antiaircraft missiles and they can only be fired as high as 4,000 metres, which would come nowhere near a commercial aircraft.

The rebels are claiming responsibility for strikes on two Ukrainian jets Wednesday.

The Information Telegraph Agency of Russia reports Militias claimed the People's Republic of Donetsk were bragging about downing a Ukrainian Air Force transport aircraft an hour before the Malaysia Airlines plane went down. Ukraine Reporter also tweeted that that commander of the Donetsk People's Army, Igor Girkin or Igor Strelkov, is taking credit for shooting down a plane he thought was Ukrainian. "We warned -- do no fly in our skies," he said according to a tweet from a Ukraine reporter.

Lidia Wolanskyj, a journalist in Yaremche, Ukraine, spoke with CTV News Channel.

She said the leader of the insurgence sent out a message boasting on Twitter “that they had shot down a Ukrainian plane at about the same time this plane was shot down…The theory is they thought it was a Ukrainian plane."

"These people actually have access to highly-sophisticated air defense missiles," Wolanskyj added. "Ukraine has not been involved in any air defense stuff. It has not been firing at aircrafts because there have not been any aircrafts on the separatist side."

The Ukrainian government is saying it has nothing to do with the incident. "We do not exclude this plane was shot down, and we stress that the Armed Forces of Ukraine did not take action against any airborne targets," said President Petro Poroshenko in a statement. "We are sure that those who are guilty in this tragedy will be held responsible."

U.S. officials have confirmed to ABC and NBC that a single surface-to-air missile took down the plane. They said it was unclear who fired the missile.

The Kyiv Post is reporting Ukraine's security agency SBU has intercepted phone conversations of separatists admitting to shooting down the plane. They were surprised it was full of civilians. One of the people recorded who is said to be an unidentified militant "cynically suggests that the Malaysia Airlines airplane could've been carrying spies, as, otherwise, it would have no business flying in that area."