UN Secretary General Kofi Annan has seen first-hand the destruction wrought in southern Lebanon during the conflict between Israel and Hezbollah.
Annan's visit included talks on an expanded UN force
Mr Annan visited UN troops at the southern port of Naqoura before flying over scenes of devastation and stopping at the village of Markaba.
The UN chief later arrived in Israel, as he continues his regional tour to try to bolster the two-week old truce.
Earlier Mr Annan met Lebanese leaders to discuss the UN peacekeeping force.
The force is to be expanded from 2,000 to 15,000 under the UN-backed ceasefire, which ended the fighting earlier this month.
Mr Annan said he would urge the Israeli government to lift its air and sea blockade of Lebanon, imposed at the start of the conflict to stop arms reaching Hezbollah.
He also called on Hezbollah to free two Israeli soldiers, whose capture on 12 July triggered the fighting.
Mr Annan flew by helicopter from Beirut to the UN peacekeepers' headquarters in Naqoura, in an area still occupied by Israeli troops and tanks.
There he reviewed an honour guard of UN troops on the lawn of the white-walled UN compound.
UN TROOP PLEDGES
France - leadership and 2,000 troops
Italy - 2,500-3,000 troops
Bangladesh - two battalions (up to 2,000 troops)
Malaysia - one battalion
Spain - one mechanised battalion
Indonesia - one battalion, an engineering company
Nepal - one battalion
Denmark - at least two ships
Poland - 500 troops
Finland - 250 troops
Belgium - 302 troops, later rising to 392
Germany - maritime and border patrols but no combat troops
Norway - 100 soldiers
After about two-and-a-half hours, Mr Annan set off on an airborne tour of some of the areas in southern Lebanon most heavily bombarded by Israel during the 34-day conflict.
Speaking in Markaba, Mr Annan said many issues remained unresolved and were becoming "serious irritants on both sides".
He said these included the issue of the captured Israeli soldiers, prisoners held by Israel, Israel's blockade of Lebanon and the need to secure Lebanon's borders.
The BBC's Jon Leyne in Naqoura says many southern Lebanese villages are in ruins and unexploded rockets, bombs and mines litter the ground.
Local people are reluctant to return to their homes near the border until the last Israelis have pulled out, our correspondent says.
Israel has said it will not withdraw until the expanded UN force is deployed alongside the Lebanese army in areas currently occupied by Hezbollah forces.
EU states have pledged some 7,000 troops towards the force's 15,000-strong target.
On Monday, the Italian government approved sending 2,500 troops - the largest national contingent so far.
The force - comprising engineers, marines, special forces and bomb disposal experts - set sail for Lebanon on Tuesday.
In Israel, Mr Annan is due to meet Prime Minister Ehud Olmert, before continuing on to Iran and Syria, countries with close links to Hezbollah.
Israel is looking for better guarantees that Hezbollah will not rearm and has said its blockade against Lebanon will remain in place until an arms embargo is implemented against the militant group.
Mr Olmert has announced that two governmental committees of inquiry will be set up into the handling of the conflict in Lebanon - one dealing with political matters, the other military affairs.
This falls short of demands for an independent state commission which would have had the power to recommend that top officials step down, the BBC's Nick Thorpe in Jerusalem reports.
Mr Olmert's critics are likely to accuse him of trying to dodge criticism, but he says there is no time for a full-blown investigation.
Speaking in Haifa on Monday, Mr Olmert admitted to "failures" during the offensive, but defended his decision to launch the campaign.