Hamish McDonald – Within seven minutes of an Indonesian army radio message being intercepted in Darwin, saying five Australian journalists had been deliberately killed in East Timor in 1975, it was translated and sent to prime minister Gough Whitlam, senior ministers and officials.

Within another hour, Royal Australian Navy radio operators and linguists at the Shoal Bay listening station were stunned to get a telephone call from the Prime Minister's Department in Canberra. "Is this report true?" an aghast official asked.

This was the evidence given yesterday at the Sydney inquest on the five journalists by retired navy linguist Robin Dix, who was on duty at the Defence Signals Directorate base at Shoal Bay on October 16, 1975.

Another former intelligence official, colonel Geoff Cameron, told the inquest that he wrote an internal Defence Department memo two days after the killings, naming captain Yunus Yosfiah as leading the Indonesian special forces attack on the East Timorese town of Balibo and holding direct command responsibility.

These accounts were different from those of Mr Whitlam and his ministers, who said then that they were trying to confirm the deaths, and decades of official public denial by Canberra about its knowledge of the Indonesian involvement.

Mr Dix, fluent in Indonesian and six other languages, said that on the afternoon of October 16, specialist radio operator Martin Hicks called him over to his place at Shoal Bay where he was listening to Indonesian military messages. As Mr Hicks wrote down a message, Mr Dix translated it: "Five Australian journalists have been killed and all their corpses have been incinerated or burnt to a crisp."

Mr Dix, 67, gave the Indonesian language text to the NSW Coroners Court, saying the word used for killed, "dibunuh", indicated deliberate intent. "I will never forget it," Mr Dix said. "I remember it word for word."

Within seven minutes, Mr Dix had given the translated message to petty officer Helen Louer, who sent it by secure channels to Defence Signals Directorate headquarters in Melbourne, from where it would have been immediately given to DSD's customers. These included the prime minister, defence minister and foreign minister and their department heads.

Within another hour, Mr Dix's Shoal Bay colleague, Ray Norton, received a telephone call, and handed the receiver over, mouthing the words "PM's Department".

"Is this report true?" asked the voice at the other end. "You are on an unsecure (or open) line," Mr Dix said he replied. "Goodbye." He hung up, and heard no more from the department.

The intercept was not among those produced by DSD for the inquest, Crown counsel Mark Tedeschi, QC, said.

Mr Dix's evidence conflicts with other testimony that intercepts gradually confirmed the deaths from October 17 on.

The head of the Prime Minister's Department at the time, John Menadue, said yesterday he could not recall anything like this intercept. "It just does not ring any bells with me," he said.

Mr Menadue said there were officials in the department cleared to receive highly classified intelligence, though Mr Whitlam generally had worked directly with the Foreign Affairs Department on Indonesia and East Timor. Mr Whitlam could not be reached for comment.