Lebanese Prime Minister Rafiq Hariri talks on his mobile phone during a parliament session in Beirut, Feb. 14, 2005, moments before he was killed in a huge explosion in central Beirut. Hasan Ibrahim/AFP/Getty Images

The leader of Hezbollah says authorities will never be able to arrest four members of his militant group who have been indicted in the murder of a former Lebanese prime minister.

Sheik Hassan Nasrallah said Saturday in a televised address that "even in 300 years" the men will not be turned in. The Shia militant group denies any role in the killing.

Nasrallah's speech marked his first comments since the indictment was announced Thursday. A high-ranking Hezbollah militant and three others were accused in the 2005 assassination of Rafik Hariri.

Nasrallah also praised the four men as "honourable" members of his group, and he denounced the six-year investigation as a plot by Israel.

The suggestion that Hezbollah was involved in the 2005 Beirut truck bombing that killed Rafik Hariri threatens to plunge this Arab nation on Israel's northern border into a new and violent crisis. Hezbollah has denied any role in the killing and vowed never to turn over any of its members.

Nasrallah said the suspects named in the indictment are brothers "who have an honourable history in resisting Israeli occupation." He went on to cast doubt on the U.N.-backed tribunal investigating the crime and said it was biased.

The case has further polarized Lebanon's rival factions Hezbollah with its patrons in Syria and Iran on one side, and a Western-backed bloc led by Hariri's son, Saad, on the other.

The bombing that killed Hariri and 22 other people on Feb. 14, 2005, was one of the most dramatic political assassinations in the Middle East. A billionaire businessman, Hariri was Lebanon's most prominent politician after the 15-year civil war ended in 1990.

In the six years since his death, the investigation has sharpened some of Lebanon's most intractable issues: the role of Hezbollah, the country's most powerful political and military force, and the country's dark history of sectarian divisions and violence.

Rafik Hariri was one of Lebanon's most powerful Sunni leaders; Hezbollah is a Shia group.

One of the men named in the indictment, Mustafa Badreddine, has a storied history of militancy. He is suspected of building the powerful bomb that blew up the U.S. Marine barracks in Beirut in 1983, killing 241 Americans, mostly Marines, according to a federal law enforcement official and a book, Jawbreaker, by Gary Berntsen, a former official who ran the Hezbollah task force at the CIA.

In his speech, Nasrallah confirmed the three others are also Hezbollah members.