Malaysia Airlines plane crashes in Ukraine
Ukraine's president says a Malaysia Airlines passenger plane which crashed in the east of the country, killing nearly 300 people, may have been shot down by a missile.
Flight malaysia airlines MH17 was en route from Amsterdam to Kuala Lumpur with 295 people on board when it disappeared from radar screens near Ukraine's border with Russia.
Vision from the crash scene shows smouldering wreckage, and there are reports that locals have seen bodies.
Ukrainian president Petro Poroshenko says the Boeing 777 may have been shot down, and media reports suggest it may have been downed by a Buk ground-to-air missile.
Ukraine and the pro-Russian separatists it is currently fighting in the east of the country have both denied shooting the plane down.
Russia's Interfax news agency says pro-Russian separatists have claimed to have found the plane's black box.
Malaysia Airlines is due to hold a press conference at 4:00am Kuala Lumpur time (6:00am AEST).
The airline said flight tracking data indicated the plane was at its cruising altitude of 33,000 feet when it disappeared.
The BBC is quoting one farm worker in the area as saying, "I was working in the field on my tractor when I heard the sound of a plane, then a bang and shots".
Another said: "There was thick black smoke from a nearby factory. From my balcony I saw a plane begin to descend from a great height and then heard two explosions."
The disaster comes just four months after Malaysia Airlines lost contact with flight MH370, another Boeing 777 carrying more than 200 people. The fate of that aircraft remains a mystery.
On Twitter, Mr Poroshenko described the incident as an attack by terrorists.
"We do not exclude that the plane was shot down and confirm that the Ukraine Armed Forces did not fire at any targets in the sky," Mr Poroshenko said in a statement posted on the president's website.
Malaysian president Najib Razak said he was "shocked".
"I am shocked by reports that an MH plane crashed," he said on his Twitter account. "We are launching an immediate investigation."
The White House says US president Barack Obama has ordered senior US officials to remain in close touch with Ukrainian officials about the downed plane.
Mr Obama has spoken to the Russian president about the crash.
"The Russian leader informed the US president about an air-traffic controllers' report that came just before their phone conversation that a Malaysian plane crashed in Ukraine," the Kremlin said in a statement.
Dutch prime minister Mark Rutte says he is shocked by the crash.
Other airlines are now avoiding east Ukrainian air space, including Germany's biggest airline Lufthansa.
"Lufthansa has decided to avoid the east Ukrainian air space by a wide margin with immediate effect," a company spokesperson said.