Hariri tribunal: UN prosecutor issues sealed indictment
International prosecutors have issued an indictment for the 2005 murder of former Prime Minister Rafik Hariri.
The UN-backed Special Tribunal for Lebanon has not yet released names of suspects, and a pre-trial judge will now decide whether to issue warrants.
Members of the Shia Islamist movement, Hezbollah, are expected to be named.
The group denies any role, but helped bring down the government last week after the prime minister refused to reject the authority of the tribunal.
The BBC's Middle East editor Jeremy Bowen says the tribunal's work has a much wider impact than finding out who assassinated Hariri.
It is part of the big confrontation in the region between the US and and its allies on one side; and Syria, Iran and their allies on the other.
Lebanon is calm at the moment, our correspondent says, but the worry is that events like these could be the spark that leads to sectarian violence, last seen in Beirut in 2008.
US President Barack Obama welcomed the indictment, and said the tribunal must be allowed to continue its work without interference.
"This action represents an important step toward ending the era of impunity for murder in Lebanon, and achieving justice for the Lebanese people," he said in a statement.
"I know that this is a significant and emotional time for the Lebanese people, and we join the international community in calling on all Lebanese leaders and factions to preserve calm and exercise restraint."
Rafik Hariri and 22 others were killed in February 2005 when a huge bomb exploded next to his motorcade in Beirut.
Syria was initially blamed for the assassination. In the wake of Mr Hariri's death, it was eventually forced to withdraw its troops from Lebanon after 29 years. In the past year, however, members of Hezbollah have emerged as prime suspects.
The Canadian broadcaster, CBC, reported in November that evidence gathered by the Lebanese police and the UN pointed "overwhelmingly to the fact that the assassins were from Hezbollah".
It published diagrams showing how investigators had traced interlinking networks of mobile phones from the vicinity of the blast that killed Rafik Hariri to Hezbollah's communications centre in south Beirut.
Hezbollah has rejected any suggestion of involvement in the assassination. Its leader, Hassan Nasrallah, has called the tribunal an "Israeli project" and warned of dire consequences if it indicts his followers.
The national unity government of Prime Minister Saad Hariri - Rafik Hariri's son - collapsed on Wednesday after he rejected Hezbollah's demand to discuss withdrawing all co-operation with the UN-backed Special Tribunal for Lebanon (STL) and denouncing any indictments
On Monday, the STL issued a statement on its website saying: "The prosecutor of the tribunal [Daniel Bellemare] has submitted an indictment and supporting materials to the pre-trial judge [Daniel Fransen]."
"The contents of the indictment remain confidential at this stage."
UN officials have said that the identity of the suspects will not be made public until Judge Fransen endorses the draft indictments and issues warrants - a process that could take two to three months.
Amid the political crisis, talks on naming a new prime minister have been postponed until next week.
And the US has become embroiled in a diplomatic spat with Lebanon's foreign ministry over the collapse of the government.
At the weekend, US ambassador Maura Connelly held talks with the independent Greek Catholic MP, Nicolas Fattoush - seen as a pivotal figure in the attempt to build a new coalition.
Lebanon's Foreign Minister, Ali al-Shami, summoned the envoy and accused her of "interference in the internal affairs of Lebanon".
The US strenuously denied the allegations, with state department spokesman Philip Crowley saying: "We are respecting Lebanon's sovereignty and we would hope other countries would as well."