The Australian Greens say the MH17 disaster is a horrific tragedy that will reverberate around the world.

"Our hearts go out to the families and friends of all those who have been killed, especially the 27 Australians reported to be on board," said Greens Leader Senator Christine Milne.

"Tragedies like these always touch many more people than we can ever know, but it is shocking news that up to 108 delegates to the 20th Annual AIDS Conference due to be held in Melbourne this weekend were on board the doomed flight.