A former security official confessed on Thursday before a military court to spying for Israel and also admitted his involvement in a deadly 2006 car bombing, an AFP correspondent in court said.
Mahmoud Qassem Rafeh, a 62-year-old retired Internal Security Forces official, confessed to having "collaborated with Israeli intelligence agents" between 1993 and 2006, the correspondent said.
Rafeh also admitted he transported car parts from Israel to Lebanon which were used in a 2006 bombing in southern Lebanon that killed brothers Mahmoud and Nidal Mazjoub, members of the Islamic Jihad group.
The trial was adjourned until October 15.
Lebanon and Israel remain in a state of war, and convicted spies face life in prison with hard labour or the death penalty if found guilty of contributing to Lebanese loss of life.
On Tuesday, rights group Amnesty International said in a statement that Rafeh, who has been in custody since 2006, alleged he was tortured and made to sign a "confession" which he had since sought to retract.
"He alleges that he was suspended from the ceiling by his wrists, threatened and degraded and later punished by being deprived of sleep when he complained about his treatment to a military investigative judge," the London-based rights organisation said.
Rafeh is accused of the murders of the Majzoub brothers, Hezbollah officials Ali Hassan Dib and Ali Saleh, and Jihad Jibril, son of Popular Front for the Liberation of Palestine-General Command leader Ahmad Jibril.
More than 70 people have been arrested in Lebanon this year in a crackdown on espionage rings, including a retired general and a policeman.