BEIRUT: U.N. chief Ban Ki-moon's fourth visit to Lebanon, which starts on Friday, is expected to focus on the controversial Special Tribunal for Lebanon (STL) and the deadly crisis in neighboring Syria.

A government source told AFP, on condition of anonymity, Ban was expected to address Lebanon's duties to the STL, a U.N.-backed court that has charged four Hezbollah operatives in the 2005 assassination of ex-premier Rafik Hariri.

Hezbollah dominates Prime Minister Najib Mikati's government, and has refused outright to cooperate with the STL.

The Syria- and Iran-backed movement was at the center of a political storm that rocked the Beirut government after Mikati transferred 32 million dollars Lebanon owed the STL from a fund allocated to the premier's office.

Lebanon's mandate with the U.N. secretary general on the Netherlands-based court expires at the end of February. Under the protocol establishing the STL, the mandate may be renewed if the court has not completed its work.

Days ahead of Ban's visit to the region, which will also take him to the United Arab Emirates, top Hezbollah official Sheikh Mohammed Yazbeck said the U.N. leader was "not welcome" in Beirut.

An analyst said the group's stance was not surprising.

"Hezbollah has never been that welcoming to Ban Ki-moon... What Hezbollah said is very much expected," said Timur Goksel, a political science lecturer at the American University of Beirut and former spokesman for the U.N. Interim Force in Lebanon (UNIFIL).

"More than Ban, I think their reaction is mainly against the U.N. reports," Goksel told AFP of U.N. Security Council resolutions 1559 and 1701 calling for the disbanding and disarmament of all groups in Lebanon other than the army.

Reports on the implementation of both resolutions regularly denounce Hezbollah's arsenal and call on the group to give up its weapons.

Hezbollah is the only Lebanese group not to have disarmed after the 1975-1990 civil war, arguing that its weapons were necessary to fight Israel.

It has repeatedly warned that its military might is not open to discussion.

According to the government source, Ban will also address the deadly crackdown on dissent in Syria, as well as its repercussions in Lebanon and border violations by Syrian troops.

Since October, six people have been killed by Syrian troops during regular incursions into Lebanon, where they have opened fire on border villages.

Lebanon and Syria share a 330-kilometre (205-mile) border but have yet to agree on official demarcation, an issue that is also on Ban's Lebanon agenda, according to the government source.

Ban's visit to Lebanon comes amid a U.N. "strategy" review of UNIFIL troops, who have been the target of several attacks in recent months.

He is expected to visit the peacekeeping force stationed at south Lebanon's border with Israel.

The U.N. chief is also slated to attend a two-day conference organised by the United Nations Economic and Social Commission for Western Asia (ESCWA) on the Arab world's transition to democracy.