A major international AIDS conference in Melbourne will be held as scheduled although some attendees lost their lives in the Malaysian airliner crash in eastern Ukraine.

An official in charge of regional communication for UNAIDS told China Daily that "it's a dark day for the conference...our thoughts are with the families."

The official also said the conference schedule hasn't changed with the opening still planned for July 20.

Previously, UNAIDS Director Michael Sidibe, who is in Melbourne, tweeted that many passengers were en route to the conference.

"At this incredibly sad and sensitive time the IAS (International AIDS Society) stands with our international family and sends condolences to the loved ones of those who have been lost to this tragedy," the conference organizers, the IAS, said in a statement.

As many as 100 conference attendees were on the doomed flight, Fairfax Media reported, including Joep Lange, a Dutch former president of the society who had spent 30 years researching and fighting the disease.