Mr Siniora is an unpopular figure for Lebanon's Hezbollah-led opposition
Lebanon's president has appointed the pro-Western incumbent Fouad Siniora to lead a new unity government.
The appointment follows a deal signed in Qatar last week to end 18 months of tension and occasional clashes between government and opposition supporters.
Mr Siniora will head a cabinet in which the Hezbollah-led opposition is guaranteed an effective veto power.
Leading pro-government figure Saad Hariri said he hoped the opposition would accept the reappointment.
"We did not nominate Prime Minister Siniora as a challenge, but for reconciliation and to turn the page," Mr Hariri told journalists.
The nomination was backed by 68 of the 127 members of parliament.
The opposition, however, made its dissatisfaction clear, saying it was against the spirit of the Doha accord.
"His nomination is a recipe for conflict rather than reconciliation," warned Christian opposition leader Michel Aoun.
Mr Aoun said the opposition would not stand in the way of forming a new government, but would not offer backing to the prime minister.
Newly installed President Michel Suleiman took up residence in south Beirut's Baabda palace on Monday after his election by parliament on Sunday.
Mr Siniora will hold consultations with political blocs later to form a new 30-member cabinet.
Western-backed ruling majority to get 16 cabinet seats and choose prime minister
Syrian-backed opposition to get 11 cabinet seats and veto power
Three cabinet seats to be nominated by president
The use of weapons in internal conflicts is to be banned
Opposition protest camps in central Beirut are to be removed
New law to divide country into smaller electoral districts
Developments come after a week of violence earlier this month in which 81 people died as Hezbollah fighters seized control of sections of the capital, Beirut.
The Shia militia backed by Syria and Iran was responding to Mr Siniora's government's attempts to outlaw its private telephone network and reassign the Beirut airport security chief, who is close to the opposition.
The opposition has been demanding Mr Siniora's resignation since its ministers resigned in 2006 after disagreements over the international tribunal on the assassination of former PM Rafik Hariri.
Under the country's sectarian power-sharing system, the prime minister must be a Sunni Muslim, the president a Christian and the speaker of the house a Shia.
The Doha accord specified that the pro-Western parliamentary majority would have 16 seats in cabinet and the opposition would have a veto-wielding 11 seats.
The remaining three ministers will be appointed by Mr Suleiman.