East Timorese freedom campaigners are mourning the death of a leading Australian human rights activist, Dr Andrew McNaughtan.

The 50-year-old was found dead in his Mosman home in Sydney's north on Christmas Eve after friends and neighbours noticed he had not been seen for some days.

Dr McNaughtan campaigned for the liberation of East Timor from Indonesian rule and was deported from the troubled province a number of times after exposing civilian murders and military oppression.

Jefferson Lee, a spokesman for the Australia-East Timor Association – for which Dr McNaughtan served as convenor in recent years – said the movement was in shock.

He said Dr McNaughtan played a major role in bringing the plight of the Timorese people to the world's attention throughout the 1990s, and sacrificed his medical career in the process.

Mr Lee described Dr McNaughtan as being "as game as Ned Kelly" in his approach, but "laudable as Ghandi" in championing the rights of oppressed people.

"I think it was just his deep-seated compassion for fellow human beings," Mr Lee said.

"He was first alerted to the Timor problem when he was working as a general practitioner in Darwin and was treating Timorese refugees and noticed all the torture marks and psychosis effects from torture."

In 1996, Dr McNaughtan and other Australians were detained by Malaysian police after attending a banned conference on East Timor at a Kuala Lumpur hotel.

A pro-government youth group allied to then Prime Minister Mahathir Mohamad's ruling coalition broke up the conference, saying it could harm Malaysia's ties with Indonesia, which annexed East Timor in 1975.

East Timor's newly appointed consul-general to Australia, Abel Guterres, was also kicked out of Malaysia alongside Dr McNaughtan. Mr Guterres said Dr McNaughtan was considering his request to spend two years practising medicine in the village where he grew up.

"Andrew was one of those very special people whose dedication to the struggle of East Timor was just so tireless," Mr Guterres said. "He was a great mate who did everything possible to help East Timor and this is a great loss."

Mr Lee said Dr McNaughtan worked on the board of Timor Aid and dispensed medical assistance to hundreds of Timorese while lobbying politicians and the media about the meltdown in East Timor.

"Dr McNaughtan was best known for his devotion to the liberation of East Timor," Mr Lee said. "He spearheaded many campaigns to highlight human rights abuses there throughout the 1990s."