PETALING JAYA: A Malaysia Airlines Boeing 777 plane has reportedly crashed in Ukraine near Russian border.
The plane, MH17, was flying from Amsterdam to Kuala Lumpur with 280 passengers and 15 crew, reports said.
Reports said that it crashed in a conflicted area near Donetsk and it would be complicated to get to the crash.
MAS sources said the plane did not enter the Russian airspace.
Sources said the plane was "shot down" while it was cruising at an altitude of 30,000ft.
Ukraine Interior Ministry said 295 people are feared dead in the crash.
The plane could have been brought down by ground-to-air missile, sources said.
MAS tweeted that "MAS has lost contact with MH17 from Amsterdam. The last known position was over Ukraine airspace."
The plane was due to travel from Amsterdam on an overnight flight to Kuala Lumpur, and was expected in the Malaysian capital at around 6:00 am on Friday (2200 GMT Thursday).
Ukrainian President Petro Poroshenko said the jet crashed over rebel-held eastern Ukraine and may have been shot down.
"We do not exclude that the plane was shot down and confirm that the Ukraine Armed Forces did not fire at any targets in the sky," Poroshenko said in a statement posted on the president's website.
Russia's UN envoy denied involvement.
"We didn't do it," Russian Ambassador Vitaly Churkin told reporters at UN headquarters in New York.
Malaysia Airlines did not immediately specify the type of aircraft involved or how many passengers were aboard.
"I am shocked by reports that an MH plane crashed," Malaysian Prime Minister Najib Razak said on his Twitter feed.
"We are launching an immediate investigation." The flag carrier and Malaysia's government are still struggling to provide answers to the mysterious March 8 disappearance of flight MH370.
The plane went missing with 239 passengers and crew on board and is now believed to have diverted off its flight path and crashed in the remote Indian Ocean.
No trace of the plane has yet been found.