A part of the wreckage of a Malaysia Airlines Boeing 777 plane is seen after it crashed near the settlement of Grabovo in the Donetsk region, July 17, 2014. [Photo/Agencies]

MELBOURNE - An influential Dutch AIDS expert was among the 298 passengers on a Malaysian airliner that was crashed over Ukraine, along with others who were headed to an international AIDS conference in Melbourne, an Australian associate said on Friday.

Joep Lange, who spent more than 30 years researching and fighting HIV and AIDS, was known for advocating cheap access to treatments in poor countries.

"Joep had an absolute commitment to HIV treatment and care in Asia and Africa," said David Cooper, a professor at the Kirby Institute at the University of New South Wales, who worked closely with Lange on an HIV research project in Bangkok.

"The joy in collaborating with Joep was that he would always bring a fresh view, a unique take on things, and he never accepted that something was impossible to achieve," Cooper said in a statement.

Australian Foreign Minister Julie Bishop said a number of people on Malaysia Airlines Flight MH17 were on their way to the 20th International AIDS Conference.

The conference, due to start on Sunday in Melbourne, features former US President Bill Clinton among its keynote speakers.

As many as 100 attendees were on the doomed flight, Fairfax Media reported, including Lange, a former president of the International AIDS Society which organises the conference.

"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," Chris Beyrer, president elect of conference organiser the International AIDS Society (IAS), told reporters in Melbourne.

"The IAS has also heard reports that among the passengers was a former IAS president, Joep Lange, and if that is the case, then the HIV/AIDS movement has truly lost a giant," he said.

Lange, a professor of medicine at the Academic Medical Center at the University of Amsterdam, pioneered development of affordable combination therapies to treat HIV and simple antiretroviral drug treatments to prevent transmission of HIV from mothers to their babies in poor countries.

He was also scientific director of the Amsterdam Institute for Global Health and Development. Institute officials were not immediately available to comment.

Lange was traveling with his partner, Jacqueline, the Kirby Institute said.

Australian Prime Minister Tony Abbott pointed the finger at Russia over the disaster and said the perpetrators must be brought to justice.

"This is a grim day for our country and it's a grim day for our world. Malaysian Airlines MH17 has been shot down over the eastern Ukraine, it seems by Russian-backed rebels," Abbott told parliament.