A Malaysian airliner carrying 295 people has crashed in east Ukraine on a flight from Amsterdam to Kuala Lumpur, amid allegations it was shot down.
There are no signs of survivors at the scene of the crash near the village of Grabovo, which is under the control of separatist rebels.
Flight MH17 had been due to enter Russian airspace when contact was lost.
Ukraine’s president called the loss of the plane an “act of terrorism” as the rebels denied shooting it down.
Separatists are believed to have shot down two Ukrainian military planes over the region in recent days.
Alexander Borodai, leader of the self-styled Donetsk People’s Republic which is defying the Ukrainian government, has been quoted as saying a truce could be agreed for “several days” to allow investigations and recovery operations to take place.
Leading airlines have announced they are now avoiding eastern Ukraine.
Russia’s emergency services have reportedly asked the Ukrainian government for permission to work at the crash site.
US President Barack Obama has said the crash of the airliner was a “terrible tragedy” and that US officials were trying to establish if any Americans had been on board.
Mr Obama spoke to Russian President Vladimir Putin about the crash earlier, the Kremlin said in a statement (in Russian).
The British government has called for an emergency meeting of the UN Security Council to discuss the crisis in Ukraine as a result of the crash.
‘Then a bang’
The plane fell between Krasni Luch in Luhansk region and Shakhtarsk in the neighbouring region of Donetsk.
Anton Herashchenko, an adviser to Ukraine’s interior minister, was quoted by the Associated Press as saying the plane had been hit by a missile at an altitude of 10,000m (32,000ft). The claim could not be verified independently.
At least 100 bodies have been found so far at the scene, an emergency services worker told Reuters, with wreckage spread across an area of up to about 15km (nine miles) in diameter.
Broken pieces of the wings were marked with blue and red paint – the same colours as the emblem of the Malaysian airline, the agency said.
“I was working in the field on my tractor when I heard the sound of a plane and then a bang and shots,” a witness called Vladimir told Reuters.
“Then I saw the plane hit the ground and break in two. There was thick black smoke.”
A separatist rebel from nearby Krasnyi Luch who gave his name as Sergei said: “From my balcony I saw a plane begin to descend from a great height and then heard two explosions.”
Ukraine’s defence ministry issued a statement saying there were no air force jets in the area, no surface-to-air systems being used against the rebels and that the plane was out of reach of other Ukrainian air defence forces.
Ukraine’s Foreign Minister, Pavlo Klimkin, told the BBC his government had proof that the plane was shot down by pro-Russian separatists. Mr Klimkin said that Kiev would publish intercepted phone conversations.
Ukrainian media have already broadcast audio purported to be conversations intercepted by the Security Service between pro-Russian militants, in which several men talk about having shot down a civilian plane.
But separatist leader Alexander Borodai accused the government of downing the airliner.
“Apparently, it’s a passenger airliner indeed, truly shot down by the Ukrainian air force,” he told Russia’s state-run Rossiya 24 TV broadcaster.
The Interfax news agency reported that rebels had found the black box flight recorder, but this has not been independently confirmed.
The UK Foreign Office said it was aware of the reports of the crash and was “urgently working to establish what has happened”.
The head of the Russian Air Traffic Controllers’ Union, Sergei Kovalyov, told BBC Russian that the airspace over eastern Ukraine had remained open during the conflict because the planes previously shot down had tended to be helicopters or low-flying fast jets.
“In order to bring down an airplane from an altitude of 10,000m, you need to have very serious weapons…. missiles,” he said. “It’s either a mistake or a terrorist act.”
Ukraine has accused Russia’s military of supplying advanced missiles to the rebels.
Earlier on Thursday, Ukrainian officials blamed the Russian air force for shooting down one of its ground attack jets on Wednesday, and a transport plane on Monday.
In 2001, Ukraine admitted its military was probably responsible for shooting down a Russian airliner that crashed into the Black Sea, killing all 78 people on board.
This is the second plane crash involving a Malaysian airliner this year, following the disappearance of Flight MH370 to Beijing in March.