The first THAI flight rerouted away from the war torn area was TG921 from Bangkok to Frankfurt, according to Manager news agency quoting Smud Poom-on, THAI's emergency and crisis response director.
THAI flights that used to pass through Ukrainian airspace travel to and from London, Frankfurt, Munich, Zurich, Rome and Paris. The rerouting was indefinite, the report said.
THAI announced on its website on Friday that none of its flights were in Ukraine airspace. Thai Airways flights to and from Europe had been rerouted to avoid the area.
Eurocontrol, the European Organisation for the Safety of Air Navigation, announced that MH17 was at Flight Level 330 (approximately 10,000 metres/33,000 feet) when it disappeared from the radar.
"This route had been closed by the Ukrainian authorities from ground to flight level 320, but was open at the level at which the aircraft was flying," Eurocontrol stated.
Since the crash, the Ukrainian authorities have informed Eurocontrol of the closure of routes at levels from the ground up in eastern Ukraine. Eurocontrol said it is rejecting all flight plans that are filed using these routes, which will remain closed until further notice.