BEIRUT (AFP) – Saudi King Abdullah will visit Lebanon on Friday and will urge rival parties to exercise restraint amid tensions over the possible implication of Hezbollah in the murder of ex-premier Rafik Hariri, a government official said on Monday.

"The visit comes amid efforts to ease tensions in the country," the high-ranking official who did not wish to be identified told AFP. "He is going to tell all the parties to remain cool."

He was referring to mounting fears of a conflict in Lebanon following last week's announcement by Hezbollah leader Hassan Nasrallah that he knew the UN tribunal probing Hariri's 2005 murder was set to indict Hezbollah members.

Nasrallah made clear that he would not accept any indictment of Hezbollah members and has questioned the credibility of the tribunal.

His announcement has sparked fears of a sectarian conflict between Sunnis and Shiites in Lebanon similar to one that brought the country close to civil war in 2008.

Saudi Arabia was a key supporter of the slain Hariri and holds sway with his son Saad Hariri, who is Lebanon's current prime minister.

The Saudi king's hours-long visit will be his first to Lebanon since 2002.

It is part of a regional tour that will also take him on Thursday to Syria, which, along with Iran, backs Hezbollah, the official said.

In Lebanon, the king will meet President Michel Sleiman and members of the national unity government that includes Hezbollah.

The Shiite party is the most powerful military and political force in Lebanon and fought a devastating war with Israel in 2006.