UK Prime Minister Tony Blair has held talks with the Lebanese government, amid angry protests against his visit.
Protesters waved flags and banners criticising Mr Blair
Thousands of demonstrators accused him of complicity in the deaths of 1,100 Lebanese civilians from Israeli bombing in the recent conflict with Hezbollah.
Mr Blair defended his position of rejecting calls for an early ceasefire, saying a UN resolution dealing with the "real problems" had been his priority.
Several protesters disrupted a news conference, shouting: "Shame on you."
Mr Blair reiterated Britain's official position during the five-week conflict that a durable resolution framed by a UN resolution was better than a "quick fix".
"Frankly the best chance for Lebanon now is the implementation of Resolution 1701," Mr Blair said.
During the five-week conflict, Israel bombed targets across Lebanon, including residential areas and civilian infrastructure, saying it was necessary to restrict Hezbollah's military activity.
The conflict followed the capture by Hezbollah of two Israeli soldiers in a cross-border raid.
Israeli military losses in clashes on the border were 116 men, while 43 civilians died in Hezbollah rocket attacks.
A ceasefire sanctioned by UN Resolution 1701 has largely held since 14 August.
Security forces sealed off Beirut's central area, where Mr Blair held talks with Prime Minister Fouad Siniora, with rolls of razor wire.
Up to 5,000 protesters gathered nearby in a stand-off with security forces, shouting slogans and waving banners describing Mr Blair as a "killer" and "war criminal".
"Tony Blair supports America and Israel and has supported the war, so how can we welcome him here?" said 21-year-old hotel worker Ali Shahine, who was among the protesters.
Mr Blair flew in after talks with Israeli and Palestinian officials
At a joint new conference with Lebanese Prime Minister Fouad Siniora, Mr Blair admitted his policies were controversial, both at home and in the Arab world, but he expressed "deep sympathy" for those who had lost family members in the Israeli bombing.
Mr Siniora praised the demonstrators for expressing their criticism in a democratic fashion within the law, a view echoed by his UK counterpart.
Lebanon's most senior Shia cleric had tried to have the visit cancelled and several Shia officials refused to attend meetings with Mr Blair, including the speaker of parliament and two Hezbollah ministers.
Grand Ayatollah Mohammed Hussein Fadlallah called on the government to declare Mr Blair persona non grata.
He said Mr Blair should have been told to stay away so he would "know we are not so naive as to welcome him when he has contributed to killing us and slaughtering our children".
Mr Blair travelled to the country after a visit to Israel and the Palestinian territories.
Hamas, the militant group heading the Palestinian Authority, rejected his proposals that it should join a unity government which recognised Israel in order for an international boycott to be lifted.
A spokesman said the group was willing to form a coalition, but it would not accept conditions imposed from outside.