The previously unheard of group sent an email to journalists across China on Sunday that read: “You kill one of our clan, we will kill 100 of you as pay back,” but the message provided no details of what brought the flight down.
Malaysia’s acting transport minister Datuk Seri Hishammuddin Hussein told reporters he doubted the claim’s legitimacy.
“There is no sound or credible grounds to justify their claims,” he said, according to Malaysian news reports.
Other officials said the claim could be a hoax aimed at increasing ethnic tensions between Uighurs and Han Chinese in the wake of the March 1 knife attacks in the southwestern city of Kunming that left 29 people dead and more than 100 others injured.
Officials say the message was delivered through an encrypted, anonymous Hushmail service that is virtually impossible to trace.
Investigators also said Monday that debris spotted from the air that was believed to be from the plane turned out to be unconnected to the aircraft.
They also said an oil slick discovered in the region was not connected to the flight.
While the exact reason for the plane's disappearance on Saturday over the South China Sea, one of the safest and most flown routes in air travel, remains a mystery, investigators said the evidence so far “appears to indicate that the aircraft is likely to have disintegrated at around 35,000 feet,” Reuters reported.
While foul play is still only speculation some are drawing parallels to the vanishing Malaysian flight and the 1980s bombings of Pan Am Flight 103 over Lockerbie and Air India Flight 182 off the coast of Ireland.
Meanwhile, Hussein has confirmed that authorities have surveillance video of the two passengers who boarded the plane using stolen passports.
Reports are circulating that authorities have reviewed surveillance tapes of the plane’s boarding and are now saying the pair were not Asian, as they had originally indicated.
“We confirmed now they are not Asian-looking males,” said an official, adding that one of the men was black.
One of the mystery men had been identified, officials said, though they refused to release a name or nationality.