BRISBANE Nov 26 AAP - An independent judicial inquiry was needed to get to the bottom of the sinking of the asylum seeker boat Siev-X and the subsequent loss of 353 lives, a former Australian diplomat said today.

Tony Kevin, former Australian ambassador to Cambodia and a witness at the Senate's Children Overboard inquiry, said he believed there was enough evidence to push for a full judicial inquiry into the incident.

The 19-metre fishing boat, loaded with more than 400 mainly Iraqi asylum seekers, sank in international waters on October 19 last year en route from Indonesia to Australia. A total of 353 people, including more than 100 children, lost their lives. Mr Kevin's call follows revelations last week the Australian Federal Police (AFP) may have been involved, or known of, the use of electronic tracking devices on board people smuggling ships leaving Indonesia.

He said a full judicial inquiry with subpoena powers was needed to either prove or disprove Australia's involvement in the incident.

He said the tracking device revelations "neatly explained" and corroborated testimony by survivors that several grey boats, which he believed to be Indonesian military boats, were seen in the area just six hours after the boat sank. "This tracking devices question could be an evidentiary breakthrough," Mr Kevin said. "It fits so well with so much else that is becoming known about the people smuggling disruption program and the history of the voyage of the (Siev-X) boat."

Mr Kevin said evidence was mounting to prove Egyptian people smuggler Abu Quessai was tasked to load up the boat very quickly and begin the voyage to Australia as part of a "sting" operation.

Further circumstantial evidence indicated two or three AFP liaison officers were likely to know "enough that they might risk long gaol sentences as accessories to this crime if they are ever brought to court".

However, he said it would unfair to blame these officers, rather responsibility lay with top levels of government, including the prime minister.

Mr Kevin is calling on the Senate's opposition parties and independents to push for a full judicial inquiry, as was done with other disasters including Thredbo and the Granville train disaster.

"We have to deal with this, we have to confront it, if we don't it is going to be niggling at our conscience because it can't be suppressed - too much is now out," he said.

Mr Kevin was speaking tonight in Brisbane at a public forum on the Siev X sinking also attended by Australian Democrats leader Andrew Bartlett. - AAP