Singapore Airlines (SIA) has apologised for posting an "insensitive" comment on social media about the Malaysia Airlines Flight MH17 crash in crisis-stricken eastern Ukraine.

Hours after the Boeing 777-200 passenger jet with 298 people on board went down on Thursday, believed shot by a surface-to-air missile, SIA posted a one-line statement on Facebook and Twitter.

It read: "Customers may wish to note that Singapore Airlines flights are not using Ukraine airspace."

The comment sparked anger among users of social media. 

"How about at least acknowledging the terrible event and sending condolences to those families and friends involved instead of this cold, classless update?," wrote a Michael Reif in response.

Hundreds of others joined in the condemnation but some defended the airline, saying it was trying to reassure customers concerned about the safety of their flight route. 

"We are aware that our Facebook and Twitter update on Friday morning may have come across as insensitive to some," SIA said in a Facebook posting late Saturday. 

"We recognise that the information could have been better communicated and we sincerely apologise if it had offended our customers and anyone else in the online community," it added. 

"The post was in response to many requests from our customers who had asked for information about our flight routes for their upcoming flights with us."

SIA acknowledged that prior to the crash it was flying the route taken by

MH17 but has since re-routed flights.

World leaders are in agreement that MH17 was blown out of the sky by a surface-to-air missile fired from rebel-controlled eastern Ukraine. 

Kiev has gone a step further, saying militias using a Russian-supplied anti-aircraft system were responsible. (AFP)