Andrea Hopkins, Canberra – Secret files released on Tuesday show the Australian government lied about its knowledge of the murder of five journalists in East Timor weeks before Indonesia invaded in late 1975, political analyst Des Ball said.

The files show the government was informed that the journalists were dead on October 16, the same day they were reported missing, Ball told reporters at a news conference at which 70,000 pages of diplomatic documents were made public.

The government did not confirm the deaths for days and six months later said investigations were still under way. Successive administrations have told parliament and the next of kin they did not know the details of the deaths. The funerals were delayed for months and only charred bits of bone were ever produced as remains.

The files expose "the most shameful episode in the history of Australian foreign policy," Ball told reporters at the release of the files at Australia's national archives. Ball, an Australian National University professor who has written a book about the events, was selected by the government to summarise his findings from the secret papers.

Australians Greg Shackleton and Tony Stewart, Britons Malcolm Rennie and Brian Peters and New Zealander Gary Cunningham, aged 21 to 29, were killed in the Timorese town of Balibo several weeks before Indonesia invaded East Timor on December 7, 1975. The files showed four of them were killed while they hid or were held in a house. Charred bones were found in the home.

A fifth body, also burned, was found nearby, which Ball said confirmed rumours that one journalist had escaped from Indonesian troops before being captured and killed in a way that is "too horrible to recount."

Ball said the files show Australia has long known about the journalists' deaths at the hands of Indonesian troops. They show "how the Australian government connived with Jakarta over Indonesia's covert invasion ... how it dealt with the killing of the five Australian-based journalists at Balibo ... and how it lied to the Australian parliament and public, including next of kin, over the ensuing quarter of a century," he said.

The documents showed then prime minister Malcolm Fraser's coalition government kept its officials in the dark, sending a team to investigate the "presumed deaths" six months later. Fraser, now head of CARE Australia, was not immediately available for comment.

Secret memos, cables and letters sent and received by the foreign department from 1974 to 1976 are being released ahead of the usual 30-year wait in a bid to clear the air over one of the most controversial events in Australian history.