Prime minister-designate Saad Hariri on Sunday accused President Michel Aoun of blocking the formation of a government of experts that would help Lebanon to secure much-needed international financial support.
Mr Hariri was giving a televised speech to commemorate the anniversary of his father’s assassination.
Rafik Hariri, 60, also former prime minister, was credited with rebuilding the capital Beirut after the civil war.
He stood down as prime minister four months before his assassination.
Earlier in the day, Saad Hariri visited the gravesite of his father 16 years after he was killed in a massive car bombing in downtown Beirut.
His murder led to the withdrawal of Syria’s military from Lebanon, marking the end of decades of hegemony.
But Hariri's killers remain at large while Beirut reels under the burden of another massive explosion that killed more than 200 people and destroyed thousands of properties in August.
Mr Hariri warned that the lack of accountability in both cases, and a renewed wave of killings that many fear might follow the recent killing of publisher and anti-Hezbollah critic Lokman Slim, will threaten the country’s stability.
“The sentence will be implemented and Ayyash will be eventually handed over,” Mr Hariri said of Salim Ayyash, a member of the Iran-backed Hezbollah, who was convicted by a UN-backed court of involvement in his father's murder.
Hezbollah has refused to surrender Ayyash to authorities.
“More importantly, the series of assassinations must stop and shall stop, otherwise, there will be a big problem in the country,” Mr Hariri said.
He warned against failing to seize the opportunity that the international community is offering Lebanon to weather its crisis.
Mr Hariri, who recently finished an international tour to rally support for his government, blamed Mr Aoun, a staunch ally of Hezbollah, for blocking the formation of a Cabinet.
He said Mr Aoun and the Free Patriotic Movement party he founded, which is led by his son-in-law Gebran Bassil, was seeking a third of the Cabinet’s seats to secure veto power over key resolutions.
Mr Hariri said he would not yield to pressure after having presented the president with a Cabinet of 18 non-partisan experts that Mr Aoun turned down.
The president accused him of breaching the constitution by failing to consult with him over the line-up, which Mr Hariri denied.
Mr Hariri said he had discussed the line-up with the president several times, and that he even nominated four candidates from a list that Mr Aoun shared with him.
The president's office said Mr Hariri proved again that he was breaching the constitution.
But the prime minister-designate said he would pursue his efforts to revive and strengthen Lebanon’s ties with the international community and Arab states that have long provided Lebanon with financial support.
