Lebanon on Monday charged 28 people, including a Saudi citizen and two French nationals, with belonging to the jihadist Islamic State group, a judicial source told AFP.
The men, only seven of whom are in custody, also face charges of seeking to carry out suicide attacks, said the source.
A Saudi citizen and one of the French nationals were arrested in June, on the basis of US intelligence, as Lebanon was rocked by three suicide bombings in less than a week.
The second French national facing charges is still at large.
The group also includes five Lebanese citizens, the source said, with the nationalities of the others accused not specified.
The men are accused of belonging to the Islamic State, formerly known as the Islamic State of Iraq and the Levant, a jihadist group that has seized territory in Syria and Iraq.
They are also accused of preparing suicide bombings, and purchasing explosives and weapons.
The Saudi citizen was arrested on June 25 in a Beirut hotel.
As police raided the hotel, the man's accomplice blew himself up, killing himself and wounding 10 people.
The French citizen was arrested the week before, also in a Beirut hotel, and is of Comoran origin.
Lebanon has been shaken by a series of bombings since the outbreak of the conflict in neighbouring Syria.
Many of the blasts have targeted areas controlled by or supportive of the Lebanese Shiite group Hezbollah, which has backed Syria's government against an uprising.
But security forces, embassies and political figures have also been targeted, and most of those killed in the attacks have been civilians.
Recent months saw a drop-off in the attacks, with officials saying the latest bombings were linked to the rising profile of the Islamic State.
The group has declared the land under its control to be a "caliphate" and deemed its leader Abu Bakr al-Baghdadi the ruler of all Muslims.
