Syrian military intelligence agents (search) abandoned their head office in Beirut Wednesday, boarding buses and driving out of the Lebanese capital in line with demands by the United States and the Lebanese opposition.

Intelligence agents and officers left in two buses and several cars at about 11:45 a.m., ending 18 years of presence in Beirut (search).

Shortly after they left, several Lebanese entered the compound and raised a Lebanese flag and pictures of former Prime Minister Rafik Hariri (search), who was assassinated in a massive bombing in Beirut last month that sparked anti-Syrian protests.

Plainclothes Lebanese security men later posted signs telling whoever owned property in the compound to contact the Lebanese army. Like all Syrian military positions, the buildings had been taken over — but not purchased — when the Syrian intelligence agents came in 1987.

Lebanese troops asked photographers to stop taking pictures of the site.

The offices were the only remnants of Syria's military presence in Beirut since the 2000 withdrawal of army positions from the capital.

Of all Syrian military forces in Lebanon, the intelligence agents dealt most directly with Lebanese, setting up checkpoints and arresting people. Lebanese must go to them to get permits and licenses or even to resolve family disputes. Syrian intelligence also have resolved disputes among Lebanese politicians.

Also Wednesday, the U.N. team appointed to investigate the Feb. 14 assassination of Hariri in a massive bombing in Beirut left the country a day after it ended its mission. The team, headed by Peter Fitzgerald, departed on a flight to Paris, airport officials said.

Fitzgerald has said he hoped to report to U.N. Secretary-General Kofi Annan within four weeks.

The evacuation of Syrian intelligence offices comes ahead of Tuesday's summit of Arab leaders in Algeria. Syrian and Lebanon agreed earlier this month that Syrian troops and intelligence agents redeploy in the eastern Bekaa Valley or withdraw to Syria before the end of the month.

On Wednesday, the Ramlet al-Baida checkpoint was still in place but the sentry post at the entrance of the compound, which includes offices and homes for intelligence officers, was demolished.

Nearby, a huge portrait of late Syrian President Hafez Assad was brought down by Syrian and Lebanese officials. The day before, a massive picture of his son, the current President Bashar Assad, was removed from the same area.

On Tuesday, two dozen Syrian agents vacated an intelligence office in Beirut's commercial district of Hamra.

The evacuation of the Syrian intelligence service has been a key demand of Lebanese opposition, which orchestrated a gigantic demonstration Monday of about 1 million people in central Beirut.

Since the Syrian army withdrew from Beirut in 2000, the headquarters of Syrian military intelligence in Lebanon has been in the town of Anjar, a few kilometers (miles) from the Lebanese-Syrian border.

Last week, Syria withdrew its military from northern and central Lebanon. This week its shut down intelligence offices in the northern towns of Halba and Qoubaiyat, several kilometers (miles) from the Syrian border, and was packing up its offices in Tripoli.

Lebanese troops took over the evacuated posts, and in Qoubaiyat, dozens of Lebanese celebrated the departure, waving flags and honking their car horns.

When these moves are finished, Syrian intelligence in northern Lebanon will be confined to three offices in the remote Akkar district.

Meanwhile, Premier-designate Omar Karami said he would send emissaries to opposition leaders to try to form a national unity government, but acknowledged it would be difficult. Opposition lawmakers have told Karami they will not join a Cabinet until all Syrian troops have left Lebanon, Syrian-allied security chiefs have been dismissed and an international inquiry has been appointed into Hariri's assassination.