At least six British nationals are believed to be among almost 300 people on board a Malaysian airliner apparently shot down over worn-torn Ukraine.
Foreign Secretary Philip Hammond called for an international investigation to establish what to happened to Flight MH17 which crashed into territory held by pro-Russian separatists as it travelled from Amsterdam to Kuala Lumpa.
The chief executive of Amsterdam’s Schiphol Airport, Jos Nijuis, said that six British nationals were known to be among the 295 people on board the Boeing 777-200 - although the nationalities of more than 90 people have yet to identified.
Speaking at the Foreign Office following emergency talks with ministers and officials, Mr Hammond said they were still working through the passenger data to establish how many Britons there were.
“I’m deeply shocked by this appalling incident and I send my heartfelt condolences to all those who may have lost family and friends. We’re determined to get to the bottom of understanding what has happened here,” he said.
“As yet we do not have any definitive information about how this incident occurred and I don’t want to speculate at this stage. We believe that there must be a UN-led international investigation of the facts.”
He said that Britain was prepared to make Air Accident Investigation Branch assets and specialists available to assist such an investigation.
There are claims the aircraft may have been shot down.
TV pictures from the scene showed a pall of smoke billowing into the sky apparently from the stricken aircraft.
Earlier on Thursday the Ukrainian authorities said one of their fighter jets was shot down by an air-to-air missile from a Russian plane and Ukrainian troops were fired upon by missiles from a village inside Russia.
The alleged episodes mark what Ukraine says is mounting evidence that Moscow is directly supporting separatist insurgents in eastern Ukraine who have substantial quantities of powerful weapons.
Ukraine said a military transport plane was shot down Monday by a missile fired from Russian territory. Security Service chief Valentyn Nalyvaichenko said he had “unconditional evidence” that Russia was involved in downing that aircraft.
The incident brings tragedy to Malaysia Airlines for the second time this year.
In March, one of its jets disappeared with 227 passengers and 12 crew on board in one of the greatest aviation mysteries of all time.
As the drama unfolded, several other passenger jets were flying through Ukrainian airspace on one of the main routes from Europe to Asia for air traffic.
Given recent events, questions are now likely to be asked about why airlines were still using the route.
Anton Gerashenko, an aide to the Ukrainian Interior Minister, said on his Facebook page that the plane was flying at an altitude of 33,000 feet over eastern Ukraine when it was hit by a missile fired from a Buk launcher.
A similar launcher was reported by journalists near the eastern Ukrainian town of Snizhne earlier on Thursday.