An Australian man facing the death penalty in Lebanon over an alleged plot to blow up a passenger jet has asked a military tribunal to free him, saying investigators forced him to sign a false confession.

Key points: Amer Khayat has been in custody since August 2017 in Lebanon

Amer Khayat has been in custody since August 2017 in Lebanon Bombs were allegedly hidden inside meat grinder and barbie doll on an Etihad flight

Bombs were allegedly hidden inside meat grinder and barbie doll on an Etihad flight AFP say Amer Khayat knew nothing about the bombs

Amer Khayat was questioned over a statement bearing his signature that said he knew he was carrying explosives hidden inside a Barbie doll that would be detonated 20 minutes into the July 2017 Etihad flight.

"It is a masquerade," he told the court.

It is alleged two bombs were hidden on an Etihad Airways flight from Sydney to Abu Dhabi. ( Flickr: ken H )

"They told me: 'Tell us your story'. It is not true."

Mr Khayat pleaded with the tribunal's panel of judges to make a decision on his case.

He has been in custody since August 2017 while authorities in Lebanon investigate him.

"Do you want me to commit suicide in prison?" he shouted in the hearing room.

"I have two daughters. I have not seen them for two years. I'm becoming crazy."

Australian Federal Police allege two bombs were hidden in the luggage of Mr Khayat by his brothers shortly before he boarded an Etihad flight from Sydney to Abu Dhabi in July 2017.

The AFP said Mr Khayat knew nothing about the bombs, which were allegedly hidden inside a meat grinder and a Barbie doll, and removed from his luggage at the last minute by his brothers because his bags exceeded Etihad's luggage allowance.

The brothers, Khaled and Mahmoud Khayat, are also Australian citizens. They have pleaded not guilty in the NSW Supreme Court to charges of planning a terrorist attack.

AFP cannot provide assistance in cases which could result in death penalty

Khaled Khayat (left) and Mahmoud Khayat were arrested by police as part of their counter-terrorism raids in Sydney on July 2017. ( Supplied )

In the Beirut tribunal, Amer Khayat questioned his ongoing detention.

"If the police [in Australia] say I have nothing to do with this, how can you say here that I have something to do with this?" he said.

The head of the tribunal, Brigadier General Hussein Abdallah, said Lebanon had repeatedly asked Australia for information about the case.

"We don't have anything from the Australian authorities, they are not cooperating," he said.

Amer Khayat's lawyer, Joceline Adib Al-Rahi, told the tribunal: "Australia won't send anything at all because we have the death penalty. You know this."

The AFP are prevented from providing assistance in international legal cases that could result in a death penalty.

General Abdallah questioned Amer Khayat about alleged admissions made by another brother, Islamic State (IS) fighter Tarek Khayat — who was captured in Syria in December 2018 and has been sentenced to death by an Iraqi court for his role with the extremist group.

General Abdallah said Tarek Khayat told interrogators the bomb plot originated with IS in Syria.

The Khayat family as children: L-R Fadi, Amer, Tarek, Iman and Waled. ( Supplied )

Tarek Khayat claimed he put an IS explosives expert in touch with his brother, Khaled, in Sydney. Tarek said explosives were mailed to Khaled, who decided they should be hidden in a meat grinder to smuggle them on a plane, said General Abdallah.

General Abdallah asked Amer Khayat about the day of the Etihad flight, when Amer allegedly took the bombs to the Etihad check-in counter in Sydney airport.

"What happened with the check-in agent?," General Abdallah said.

"She said there was too much weight … I don't know what Khaled did. He went and took away stuff," Amer replied.

He said it was his brother who removed items from the bags, not him.

"He was holding my luggage. He had the trolley, I didn't," Amer said.

"Did you see the meat grinder?" General Abdallah asked.

"Yeah. It was just a meat grinder," Amer Khayat said.

"Did you ask your brother why he was sending a meat grinder in your luggage?" General Abdallah asked.

"He said it was a gift," Amer said.

Amer Khayat's hearing in Lebanon will resume on March 13.