Finance Minister Ali Hassan Khalil said on Tuesday that Lebanon was not forming a new government fast enough and he had not seen serious headway made on the matter.
Political leaders and foreign donors have said Lebanon, which held a parliamentary election on May 6, needs to establish a government quickly to maintain confidence in the country and get to work on reforms to help an ailing economy.
"It is important for political forces to be aware that time is not on our or anyone's side. Therefore we urgently need to accelerate...the formation of a new government," Khalil said in a statement from his office.
"We have not seen serious movement in forming a government so far. As finance minister I repeat my warning and stress the need to speed it up so that the new government can get to work on the source of the problems and work on fixing them."
Following May's election, Lebanon is being run by a caretaker government while Prime Minister-designate Saad al-Hariri forms a new cabinet.
Lebanon is the world's third-most indebted nation with a debt-to-GDP ratio of more than 150 percent. It climbed from around 130 percent in 2011, before war in neighbouring Syria, and the arrival of more than a million refugees, depressed growth and paralysed government decision-making.
The dire economic situation and unsustainable public debt levels are top priorities for the next government.
The International Monetary Fund has said Lebanon's debt trajectory is unsustainable and needs immediate action, otherwise debt-to-GDP could hit 180 percent by 2023.