The total number of dead in the crash of a Malaysia Airlines plane in eastern Ukraine is more than 300 and includes 23 U.S. citizens, a Ukrainian interior ministry aide said.
"More than 300 innocent people have been killed ... it is known that 23 U.S. citizens were killed," Zoryan Shkyryak was quoted by Interfax news agency as saying.
Earlier, a Ukrainian interior ministry official said a Malaysian airliner was shot down over eastern Ukraine by pro-Russian militants on Thursday, killing all 295 people aboard.
Raising the stakes in the East-West showdown between Kiev and Moscow, the official blamed "terrorists" using a ground-to-air missile and Ukraine's prime minister called the downing of the flight from Amsterdam to Kuala Lumpur a "catastrophe".
A Reuters correspondent saw burning wreckage and bodies on the ground at the village of Grabovo, about 40 km (25 miles) from the Russian border in an area where pro-Russian rebels have been active and have claimed to have shot down other aircraft.
Dozens of bodies were scattered around the smouldering wreckage of a passenger jet that crashed in eastern Ukraine, a Reuters reporter said.
An emergency services rescue worker said at least 100 bodies had so far been found at the scene, near the village of Grabovo, and that debris from the wreckage was scattered across an area up to about 15 km (nine miles) in diameter.
The Boeing 777 came down near the city of Donetsk, stronghold of pro-Russian rebels, interior ministry official Anton Gerashchenko said on Facebook, adding it was "shot down with a Buk anti-aircraft system by terrorists" - the term the Kiev government uses for militants seeking to unite eastern Ukraine with Russia. The dead were 280 passengers and 15 crew.
Malaysia Airlines said on its Twitter feed it had lost contact with its flight MH-17 from Amsterdam. "The last known position was over Ukrainian air space," it said.
A rebel leader said Ukrainian forces shot the airliner down. Ukrainian official said their military was not involved.
Interfax-Ukraine quoted another Ukrainian official as saying the plane disappeared from radar when it was flying at 10,000 metres (33,000 feet), a typical cruising altitude for airliners.
Ukraine has accused Russia of taking an active role in the four-month-old conflict in recent days and accused it earlier on Thursday of shooting down a Ukrainian Sukhoi Su-25 fighter jet - an accusation that Moscow denied.
The military commander of the rebels, a Russian named Igor Strelkov, had written on his social media page shortly before the report of the airliner being downed that his forces had brought down an Antonov An-26 in the same area. It is a turboprop transport plane of a type used by Ukraine's forces.
Reactions:
Russia's state-controlled Aeroflot will no longer fly over Ukraine, an official at the airline said, following the crash of a Malaysian passenger airliner in eastern Ukraine.
Itar-Tass news agency quoted Russia's Emergencies Ministry as saying there were no Russians on board the plane.
As well, Turkish Airlines said all of its flights would avoid Ukrainian airspace after a Malaysian airliner crashed in the east of the country.
This comes as U.S. President Barack Obama and Russian President Vladimir Putin discussed a downed passenger plane along the Russian-Ukraine border during a phone call in which Obama warned Moscow of more sanctions if it does not change course in Ukraine.
"I can confirm that President Putin near the end of this morning's phone call with President Obama noted the early reports of a downed passenger jet near the Russia-Ukraine border," White House spokesman Josh Earnest said.
Earnest, briefing reporters on Obama's Air Force One flight from Washington to Delaware, said Obama was briefed by his advisers on the crash and directed top U.S. officials to remain in close contact with Ukrainian officials.
For his part, Malaysian Prime Minister Najib Razak said he was shocked by reports a Malaysia Airlines plane had gone down over Ukraine and he was launching an investigation.
"I am shocked by reports that an MH plane crashed. We are launching an immediate investigation," Najib said on his Twitter feed. MH is the code for Malaysia Airlines.
In turn, Ukrainian President Petro Poroshenko believes a "terrorist act" was the cause of a Malaysian airlines passenger plane crashing, his press secretary said.
"Poroshenko thinks this of the plane that was brought down: it is not an incident, not a catastrophe, but a terrorist act," Svatoslav Tsegolko said.
Dutch PM:
The Dutch prime minister is on his way back to the Netherlands from a summit in Brussels after a Malaysia Airlines plane that took off from Amsterdam was downed in Ukraine, he said in a statement on Thursday.
"I am deeply shocked by the dramatic reports on the crash of of Malaysia Airlines MH17," he said, noting that he had been in touch with Ukraine's president. Tour operators have told local media they had booked dozens of Dutch citizens onto the flight.
"Much is still unclear about the facts, circumstances and the passengers," he said of the flight, which is listed on flight-tracking websites as sharing planes on some routes with Dutch national airline KLM.
U.S sanctions:
Ukrainian Prime Minister Arseny Yatseniuk said new sanctions imposed on Moscow by the United States and the European Union showed Russian attempts to split Washington and Brussels were not working.
Speaking to his government, Yatseniuk also told Russia to stop supplying weapons to rebels in eastern Ukraine, who have been forced to retreat into the region's two main cities after Kiev stepped up what it calls its "anti-terrorist operation".
Also on Thursday, German industry expressed concern that business with Russia will suffer further after the European Union stepped up sanctions on Moscow for not doing enough to ease the crisis in Ukraine.
Jens Nagel of Germany's BGA trade association said Brussels and Washington had no choice but to toughen sanctions on Russia even though it would hurt firms, but added that he was worried the process would keep "spiralling" upwards.
In turn, Russia's central bank said that the impact of U.S. sanctions over the Ukraine crisis would largely have a delayed impact and that it had enough tools to address short-term difficulties.
Earlier, the Moscow-based Association of European Businesses voiced "strong disagreement" with new U.S. sanctions on Russia over the Ukraine crisis, saying they would hurt economic growth "not only in Russia".
Russia's Novatek:
Russia's No.2 natural gas producer Novatek said on Thursday its key projects would go ahead despite new U.S. sanctions imposed over Moscow's actions in Ukraine.
It said the sanctions did not hurt the company's production and commercial activity. Novatek also pledged to take the "necessary measures" to finance its LNG projects with its international partners.
Novatek owns the controlling stake in Russia's Yamal LNG projects. Its partners there are France's Total and China's CNPC.
Kremlin:
Russia does not want war with its "brotherly nation" Ukraine, the Kremlin's Security Council said on Thursday, adding it only sees a political solution to the conflict there.
"We don't want war with Ukraine. For us, that would be counterproductive because in that case we would be fighting a brotherly people," Evgeny Lukyanov, deputy secretary of the body that advises President Vladimir Putin on security, said.
REUTERS