By Kim Ghattas
BBC News, Beirut
The UN Secretary General, Kofi Annan, is sending a team of experts to Lebanon to investigate the killing of the former prime minister, Rafik Hariri.
Many Lebanese blame the government and Syria for the killing
The decision was taken after the UN Security Council asked that he report on the circumstances, causes and consequences of the killing.
The investigative team will be led by Ireland's deputy police commissioner, Peter Fitzgerald.
It is still unclear how the Lebanese government will respond.
The team is expected to arrive in Beirut in the next few days.
The minister of interior, Suleiman Franjieh, has rejected all calls for an international investigation, saying only that Swiss experts would be asked to assist a Lebanese team.
The Lebanese authorities appear set for a serious stand-off with the international community.
Lebanon's defence minister, Abdalrahim Murad, has now also criticised the French president, Jacques Chirac, for his private condolence visit to Rafik Hariri's family in Beirut on Wednesday.
Mr Murad accused the French leader of snubbing the government and encouraging the opposition.
On Friday, the anti-Syria opposition called for a peaceful uprising to bring down the government, and repeated its demands for a withdrawal of Syrian troops.
But Mr Franjieh said the government would not tolerate any unrest.
He threatened to send the army to clamp down on protesters who have been taking to the streets since Monday's deadly blast.