Lebanon and Israel have officially been at war for decades, and Lebanese security services have arrested dozens of people on suspicion of working for Israel, many of whom were recruited online following the country's economic collapse beginning in 2019.

The Hezbollah source said it had detained a Syrian-Palestinian national, who also holds Ukrainian citizenship, in September after he parked a motorbike on a road leading to Beirut airport through the city's southern suburbs -- where the Iran-backed militants exercise a de facto security role.

The motorbike "was planted with an explosive device disguised as a battery", the source said, requesting anonymity to discuss security issues.

Hezbollah held the man until its war with Israel erupted earlier this month.

On March 6, Israel's military struck a building in the southern suburbs next to where he was being detained, enabling him to escape to the Ukrainian embassy, the source added.

Lebanon's General Security agency said it managed to arrest five alleged members of the group that had been working with the man and referred them to the judiciary.

Hassan Choukeir, head of General Security, told AFP that "the Ukrainian embassy in Lebanon contacted us on March 10 requesting us to authorise its citizen... who was present there and had lost his passport, to leave through Beirut airport".

"After checking his name and photograph, we became aware that he is wanted by the Lebanese judiciary and is the subject of a number of search and investigation notices from Lebanese security agencies," he added.

Choukeir said authorities told the embassy it was obliged to hand the man over, adding he was "wanted for involvement in a cell belonging to Israel's Mossad planning assassinations and bombings in Beirut's southern suburbs".

The Ukrainian embassy did not respond to AFP's requests for comment.

Since the start of its war against Hezbollah, Israel has been carrying out almost daily strikes on Beirut's southern suburbs.

In October a judicial source told AFP that more than 30 people had been arrested on suspicion of providing Israel with precise information on Hezbollah facilities and the movements of its members during its previous war with Israel in 2023 and 2024.

People convicted of working for Israel have been sentenced to up to 25 years in prison in the past.