Several passengers aboard the Malaysian jet shot down over Ukraine were world-renowned researchers on their way to an international Aids conference in Australia, it has emerged.
"A number of people" on board the Boeing 777 were en route to the southern city of Melbourne for the 20th International Aids Conference which starts on Sunday, Australian foreign affairs minister Julie Bishop said.
At least 27 Australians were confirmed to be on board the plane, which was due to continue flying to the western Australian city of Perth after stopping in Kuala Lumpur, Ms Bishop said.
Among the passengers was former president of the International Aids Society Joep Lange, a well-known HIV researcher from the Netherlands.
"There are Australians who would have planned to be at the airport tomorrow night to greet friends and family - amongst them, some of the world's leading Aids experts," opposition leader Bill Shorten said in parliament.
"The cost of this will be felt in many parts of the world."
Chris Beyrer, president-elect of the International Aids Society, said if reports of Mr Lange's death were true, "then the HIV/Aids movement has truly lost a giant".
Nobel laureate Dr Francoise Barre-Sinoussi, co-discoverer of the Aids virus and president of the International Aids Society, paid tribute to Mr Lange in a speech in the Australian capital Canberra.
"Joep was a wonderful person - a great professional ... but more than that, a wonderful human being," she said.
"If it is confirmed, it will be a terrible loss for all of us. I have no words, really, to try to express my sadness. I feel totally devastated."
Former US president Bill Clinton will deliver an address at next week's Aids conference, which brings together thousands of scientists and activists from around the world to discuss the latest developments in HIV and Aids research.
Australian House of Representatives speaker Bronwyn Bishop called for a moment of silence in parliament to honour the victims, adding that she was due to address the Aids conference on Monday.
"I know there will be many empty spots," she said. "And I think that what we're doing is mourning with all of the world and all that had been lost. And we want to see justice but in a measured way."
The International Aids Society issued a statement expressing its grief over the news that several of its colleagues and friends were on board.
"At this incredibly sad and sensitive time the IAS stands with our international family and sends condolences to the loved ones of those who have been lost to this tragedy," the group said.