U.S. Says Malaysian Jet Crash 'Terrible Tragedy', Paris Urges Probe

President Barack Obama said Thursday the crash of a Malaysian airliner in eastern Ukraine was a "terrible tragedy" and said U.S. officials were trying to establish if any Americans were on board, as the UK expressed “shock” and France urged an immediate probe.

"The world is watching reports of a downed passenger jet near the Russia/Ukraine border. And it looks like it may be a terrible tragedy," Obama said, before going ahead with a previously scheduled event in Wilmington, Delaware.

Obama said his first priority was to determine whether there were any U.S. citizens aboard the crashed jet.

"I have directed my national security team to stay in close contact with the Ukrainian government," Obama said.

"The United States will offer any assistance we can to help determine what happened and why.

"And as a country, our thoughts and prayers are with all the families of the passengers, wherever they call home," Obama said, before continuing with his remarks highlighting plans to revive America's transportation infrastructure.

U.S. Vice President Joe Biden told Ukrainian President Petro Poroshenko the United States was ready to help probe the incident.

Biden called Poroshenko after the jet came down, a U.S. official said, as the Kiev government and separatist rebels accused each other of bringing down the plane, carrying 295 people.

Earlier, the White House said that reports that the Malaysia Airlines plane had crashed in eastern Ukraine had come through while Obama was on the phone with President Vladimir Putin, and that the Russian leader had noted them during their conversation.

Malaysia Airlines flight MH17 came down near the town of Shaktarsk, in the Donetsk region of eastern Ukraine. Ukrainian President Petro Poroshenko said it may have been shot down.

Meanwhile, British Prime Minister David Cameron said he was "shocked" over the incident.

Writing on Twitter, Cameron said: "I'm shocked and saddened by the Malaysian air disaster."

He added that government officials were meeting "to establish the facts."

British media have reported that between five and ten British citizens were on board MH17, which disappeared from radar contact around 1415 GMT as it was flying over the Russian-Ukranian border.

A British Foreign Office spokesman told Agence France Presse: "We're not going into numbers. Our first priority is to establish if any British nationals are involved."

Earlier, French Foreign Minister Laurent Fabius said at least four French nationals were on board the Malaysia Airlines flight.

"A probe must be immediately launched into this major tragedy," he added, speaking during an official visit to Ivory Coast.

President Francois Hollande for his part said in a statement that he was "extremely saddened" by the disaster and expressed solidarity with families of the victims.

Meanwhile, Dutch Prime Minister Mark Rutte said that he was "deeply shocked" by the crash of the Malaysian passenger plane.

"I am deeply shocked by this dramatic news," he said in a statement over the crash of MH17, which was flying from Amsterdam to Kuala Lumpur.