Saad Hariri has arrived Saturday in France from Saudi Arabia. Image Credit: AP

Beirut - Lebanese Prime Minister-designate Saad Hariri on Tuesday blamed the Iran-backed Hezbollah for what he called a "big obstacle" in efforts to form a new government, indicating there could be no solution if it did not back down.

At a press conference in Beirut on Tuesday, Saad Hariri said "it's Hezbollah, full stop," when asked who was blocking the formation of a government. He says the Shiite militant group bears full responsibility for the consequences, including Lebanon's flagging economy.

The formation of a new government is necessary before any moves can be made towards fiscal reforms which the International Monetary Fund said in June are needed immediately to improve debt sustainability.

Hezbollah's demand for one of its Sunni allies be given a portfolio in the new Lebanese government is at the heart of a row that has obstructed a final agreement six months since a parliamentary election.

"The truth is that formation of the government hit a big obstacle," he told a televised news conference in Beirut, six months after a parliamentary election that triggered complex negotiations to form a government.

"The consequences that the country will bear are Hezbollah's responsibility" if a new government cannot be formed, he added.

More on Lebanon Government Formation

Lebanon has the world's third largest public debt as a proportion of the economy and stagnant growth. It is in dire need of a government able to make economic reforms.

Rival parties have jostled over how many cabinet positions each faction should get in the new national unity government, and over the most important jobs.

The cabinet is supposed to reflect both the representation of Lebanon's main parties and its major religious sects.

Hariri said there could be no solution to the impasse as things stood and reiterated that he would not accept Hezbollah's demand regarding the cabinet portfolio.

"The government is a national, security and social need ... This mission is for me and President (Michel Aoun). I have done everything I can and everyone has to shoulder his responsibilities," Hariri said.

President Michel Aoun vowed earlier on Saturday to find a solution to the problem. Though a political ally of Hezbollah, Aoun has sided with Hariri in the row.

In a televised speech on Saturday, Nasrallah said his group will not be compelled by threats or sanctions to give up its rocket a capability, urging his government in comments Saturday to contend with the diplomatic pressure it faces.

Lebanon's political system requires government positions to be allotted along sectarian lines.

Nasrallah said rejecting a Sunni ally from its "March 8" camp amounted to exclusion of a section of Lebanese.

"If it is forbidden, come let's talk again from the start," he said, adding: "We don't want conflict, or tension, or escalation."

Hezbollah is proscribed as a terrorist group by the United States.