Lebanese Prime Minister Rafiq Hariri has resigned, a statement from the Lebanese president's office has said.
There had reportedly been divisions within the government
Mr Hariri submitted his resignation at a meeting with President Emile Lahoud in the presidential palace, the statement said.
Mr Lahoud asked Mr Hariri to stay on in a caretaker role, his office said.
Lebanon's Future television station, owned by Mr Hariri, said that the president's consultations with legislators on a new government could begin as early as Wednesday morning.
Mr Hariri, who has been in power for nine of the past 11 years, had been expected to form the next government, which is planned to be more broadly based.
The statement did not give any reason for the move, however a change of government - delayed due to the war in Iraq - had reportedly been a subject of discussion for several months following internal divisions and economic problems within the country.
Under a power-sharing arrangement reached following the end of
Lebanon's 15-year civil war in 1990, the post of prime minister is
always held by a Sunni Muslim and the presidency by a Maronite
The speaker of parliament is Shia Muslim and the country's cabinet is divided equally among Christians and Muslims.
A 58-year-old billionaire businessman who made his fortune in Saudi Arabia, Mr Hariri is credited with launching a multi-billion dollar programme to rebuild Lebanon's shattered infrastructure following its civil war.
He also has interests in banking, real estate, oil and manufacturing, and owns a television and a radio station and a newspaper in Lebanon.