Relatives of passengers onboard the downed Malaysia Airlines flight MH 17 arrive at Kuala Lumpur International Airport in Sepang July 18, 2014. [Photo/Agencies]

SANCTIONS

Ukrainian President Petro Poroshenko, who had stepped up an offensive in the east, spoke to Obama and sought to rally world opinion behind his cause. "The external aggression against Ukraine is not just our problem but a threat to European and global security," he said in a statement.

Shock, fear and sadness after MH17 crash

Malaysia Airlines plane crashes in Ukraine

The scale of the disaster could prove a turning point for international pressure to resolve the crisis, which has killed hundreds since protests toppled the Moscow-backed president in Kiev in February and Russia annexed the Crimea a month later.

Russia, which Western powers accuse of trying to destabilise Ukraine to maintain influence over its old Soviet empire, has accused Kiev's leaders of mounting a fascist coup. It says it is holding troops in readiness to protect Russian-speakers in the east - the same rationale it used for taking over Crimea.

As word came in of what might be the worst ever attack on a civilian airliner, Obama was on the phone with Putin, discussing a new round of economic sanctions that Washington and its allies have imposed to try to force Putin to do more to curb the revolt against the new government in Kiev.

Obama warned of further sanctions if Moscow did not change course in Ukraine, the White House said.

NATIONAL MOURNING IN NETHERLANDS

Reuters journalists saw burning and charred wreckage bearing the red and blue Malaysia Airlines insignia and dozens of bodies in fields near the village of Hrabove.

"I was working in the field on my tractor when I heard the sound of a plane and then a bang," one local man told Reuters at Hrabove, known in Russian as Grabovo. "Then I saw the plane hit the ground and break in two. There was thick black smoke."

An emergency worker said at least 100 bodies had been found so far and that debris was spread over 15 km (9 miles).

The airline said it was carrying 283 passengers and 15 crew.

The Netherlands declared a day of national mourning for its 154 dead. Twenty-eight passengers were Malaysian, 27 Australian, 12 Indonesian, nine British, four German, four Belgian, three Filipino and one Canadian. All 15 crew were Malaysian. Nationalities of the others aboard were unclear.

Ukrainian officials accused rebels of using a Soviet-era SA-11 missile system acquired from Russia - offering evidence that they may have believed they were firing on a Ukrainian military aircraft.

The Ukrainian government released recordings it said were of Russian intelligence officers discussing the shooting down of an aircraft by rebels they were supporting. Supposedly timed within minutes of the last radar contact with MH-17 around 4:20 p.m. (1320 GMT), they suggested militants thought they had hit a Ukrainian military plane before finding the airliner remains.

"Hell," says one of those being recorded. "It's almost 100 percent certain that it's a civilian plane. Bits were falling in the streets ... Bits of seat, bodies."

After the downing of several Ukrainian military aircraft in the area in recent months, including two this week, Kiev had accused Russian forces of playing a direct role.

Separatists were quoted in Russian media last month saying they had acquired a long-range SA-11 anti-aircraft system.

International air lanes had been open in the area, although only above 32,000 ft (9,750 metres). The Malaysia plane was flying 1,000 ft higher, officials said. The area was closed to flights afterwards.

Some international airlines, including Australia's Qantas Airways and Korea's two major carriers, shifted the route taken by flights operating over Ukrainian air space months ago amid increasing tensions between Kiev and pro-Moscow rebels.

The US Federal Aviation Administration issued an order prohibiting American aircraft from flying over eastern Ukraine.

At the airport in Kuala Lumpur, relatives of those aboard gathered, hoping for word.

Akma Mohammad Noor said her sister, Rahimah, was on the flight, coming home for the first time in years to mark the Muslim festival of the end of Ramadan.

"We were supposed to celebrate," Noor said, weeping.

Top 5 deadliest attacks on commercial airliners  Since 1967 more than 700 people have been killed in 19 separate incidents involving live-fire attacks, according to UK-based aviation consultancy Flightglobal Ascend.