The leader of militant group Hezbollah has confirmed that a UN investigation into the killing of a Lebanese prime minister questioned Hezbollah members.
Former PM Rafik Hariri and 22 other people were killed in Beirut in a massive blast in 2005.
His allies accused Syria of involvement in the attack, which it denied. Hezbollah has close ties with Damascus.
This is the first time Hezbollah leader Hassan Nasrallah has confirmed that members of the group were questioned.
He said they had been given assurances that they were being questioned as witnesses and not suspects.
"Accusing individual members of our party is equivalent to accusing Hezbollah, that would take Lebanon to a very difficult place," Mr Nasrallah told Hezbollah's al-Manar television station.
"We will not remain silent if we find we are facing political accusations," he said.
In an official report published at the beginning of March, the UN tribunal, based in The Hague, said it was close to identifying the suicide bomber responsible for the killing.
That sparked press speculation the UN investigators were about to name Hezbollah operatives as suspects.
It was not until Thursday that Mr Nasrallah confirmed that 12 Hezbollah supporters had been interviewed in the past few weeks, and that six more had been summoned.
"We will co-operate, Hezbollah has nothing to fear," he said.
Last April, four Lebanese generals accused of Mr Hariri's murder were released from custody because the evidence against them was deemed to be insufficient.
In 2008, 100 people died in clashes between Hezbollah and supporters of Rafik Hariri's son Saad, now Lebanon's prime minister.