Hezbollah chief Hassan Nasrallah urged all Lebanese to boycott a UN-backed probe into ex-premier Rafiq Hariri's murder, warning that cooperation amounted to an attack on his militant group.
The Hague-based tribunal investigating the 2005 assassination in a massive bombing, in which 22 other people were also killed, condemned the call as a "deliberate attempt to obstruct justice".
Lebanon is facing a full-blown crisis after reports that the Special Tribunal for Lebanon (STL) is set to accuse members of the powerful Shiite militant group Hezbollah over the murder of Hariri, a Saudi-backed Sunni.
"I call on all Lebanese, citizens... and politicians alike, to boycott the investigators of this tribunal and end all cooperation with them," Nasrallah said.
"We have reached a very dangerous point where our honour has been breached," he said in a televised address in which he charged that the probe was passing on information to Israel, his militia's arch-foe.
"Any further cooperation with these investigators is equal to an attack on the resistance," he added, referring to his Syrian- and Iranian-backed movement.
Nasrallah has confirmed that several of members of his movement, both male and female, have been interrogated in connection with the killing.
His call for a boycott came a day after angry women attacked two STL investigators at a gynaecology clinic in a Hezbollah-controlled southern suburb of Beirut.
The investigators had requested information on patients from the clinic's head doctor and were leaving her office when about 30 women charged at the pair and snatched a briefcase from them.
The office of STL prosecutor Daniel Bellemare said that such incidents would not deter the investigation.
Hezbollah has also accused the United Nations of interfering in Lebanese affairs and called instead for a local investigation.
But Prime Minister Saad Hariri, a son of the slain former premier, has vowed to see the UN tribunal through.
"Any call to boycott the Tribunal is a deliberate attempt to obstruct justice," a STL spokeswoman told AFP in The Hague.
"The STL will continue to rely on full cooperation by the Lebanese government and the support of the international community in fulfilling its mandate," she said.
Nasrallah on Thursday said his party was bracing to face an STL accusation towards the end of the year.
"The indictment was written in 2006 and it is a carbon copy" of what has been published in the German magazine Der Spiegel, the French daily Le Figaro and elsewhere, he said, referring to articles that appeared last year and were allegedly based on leaks from the tribunal.
The Shiite leader said the UN investigators had encroached on Muslim sensitivities with the visit to the gynaecology clinic and accused the tribunal of being another channel for Israeli intelligence.
"Why would the investigators go to a clinic that is frequented by the daughters, sisters and wives of Hezbollah leaders?" Nasrallah asked. "How are our women's medical files necessary to the investigation?
"We have long known that every piece of information given to the tribunal was passed on to Western intelligence, but we were silent," he added.
"Why were we silent? Solely to avoid being told we were obstructing the tribunal, out of respect for Hariri and his family and others.
"But we now have reached a point where we can no longer keep silent for anyone's sake," said Nasrallah.
Hours earlier UN special envoy for Lebanon Terje Roed-Larsen said Lebanon was in a "hyper-dangerous" state and warned of "a hurricane blowing up" in the Middle East.
The US ambassador to the United Nations, Susan Rice, meanwhile accused Syria and Iran of fuelling tensions in Lebanon by supplying illicit arms to their ally Hezbollah.© ANP/AFP