Saudi Arabia on Wednesday abandoned efforts to mediate in Lebanon's political crisis, warning of a "dangerous" situation as all eyes turned to a Turkish-Qatari bid to defuse tensions.

In an interview with the Saudi-owned Al-Arabiya television news channel, Foreign Minister Prince Saud al-Faisal said the Saudi king was "pulling his hand" from Lebanon.

He said the monarch -- whose country is a key ally of Lebanon's embattled caretaker Prime Minister Saad Hariri -- took the decision after Saudi-Syrian efforts for rival camps in the tiny Mediterranean country to reach a compromise failed.

Faisal said the King and Syrian President Bashar al-Assad had endeavoured in recent months to address the situation in Lebanon as a "whole".

"When that did not happen, the (king) said he was pulling his hand out," Faisal said.

He added that the situation was "dangerous" and could lead to the partitioning of the multi-confessional country.

Lebanon is mired in a deep political crisis stemming from a dispute between the US-backed Hariri and the Iranian- and Syrian-backed Hezbollah over a probe into the 2005 assassination of Hariri's father, ex-premier Rafiq Hariri.

The prosecutor of the UN-backed Special Tribunal for Lebanon (STL) on Monday submitted an indictment in the case.

Hezbollah has said it expects party members to be implicated by the STL, which it accuses of being part of a US-Israeli plot.

The Shiite party, which is the most powerful military force in the country, last week forced the collapse of Hariri's unity government because of the dispute.

Turkey's Foreign Minister Ahmet Davutoglu and Qatari Prime Minister Sheikh Hamad bin Jassem bin Jaber al-Thani have been leading efforts in the past few days to defuse the crisis amid mounting fears of sectarian violence.

The two leaders on Tuesday met separately with Lebanese President Michel Sleiman, parliament speaker Nabih Berri and Hariri.

They also met with Hezbollah chief Hassan Nasrallah, who lives in hiding for fear of assassination.

The diplomatic efforts are reportedly focused on reviving the failed Syrian-Saudi initiative which reportedly called for Hariri to disavow the STL against guarantees from Hezbollah concerning its weapons arsenal.

Consultations on forming a new government are scheduled to begin next Monday but experts and politicians have predicted a protracted crisis that could lead to similar violence as that which brought the country close to civil war in May 2008.

Tension soared on Tuesday after dozens of black-clad unarmed Hezbollah supporters appeared on the streets of several neighborhoods of west Beirut, prompting schools to shut down and the army to deploy in those areas.

"What happened on the ground Tuesday marks the beginning of a series of unprecedented progressive measures that could surprise many," said the Arabic-language As-Safir, which is close to Hezbollah.

"It seems that the language of the street is back," added the daily An-Nahar, close to Hariri's camp.

It was referring to sectarian Sunni-Shiite violence in 2008 in which some 100 people were killed.