Spain's defense minister arrived in southern Lebanon Monday to collect the bodies of six U.N. peacekeepers slain in a car bombing, as the U.N. commander stressed the force remained committed to keeping the peace between Lebanon and Israel.

Nobody has claimed responsibility for the bombing Sunday that killed six members of the Spanish contingent, including three Colombians, and seriously wounded two others. But the anti-Syrian coalition in parliament blamed Damascus, despite its condemnation of the bombing.

Before flying to the Marjayoun area of southern Lebanon near the border with Israel where the contingent has its headquarters, Spanish Defense Minister Jose Antonio Alonso called the bombing a "premeditated attack" and said the "most likely cause" was a car bomb or device activated by remote control.

The peacekeepers were patrolling the main road between the towns of Marjayoun and Khiam, a few kilometers north of the Israeli town of Metulla, when the bomb struck their armored personnel carrier.

Alonso said Sunday that three Colombian and two Spanish peacekeepers were among the dead.

Spain has 1,100 peacekeepers in Lebanon, part of the 13,000-member U.N. Interim Force in Lebanon from 30 countries, which first deployed in Lebanon in 1978 and was reinforced in the last year. UNIFIL, along with 15,000 Lebanese troops, patrols a zone along the Lebanese-Israeli border.

UNIFIL's presence puts teeth in U.N. cease-fire resolution 1701 that halted last summer's 34-day war. Southern Lebanon has been largely quiet after the summer war killed more than 1,200 people, most of them in Lebanon.

The attack, the first since UNIFIL was reinforced following last year's war, came as the U.N. has become increasingly involved in highly divisive issues in Lebanon, including its tense relations with neighboring Syria. U.N. resolutions have dealt with Lebanon's borders with Israel and Syria, Palestinian guerrilla and Hezbollah weapons, as well as an international tribunal to try the killers of former Prime Minister Rafik Hariri.

The UNIFIL commander, Gen. Claudio Graziano of Italy, called the attack the "most serious incident" since the end of the Hezbollah-Israel war, saying "the perpetrators not only targeted UNIFIL but peace and security in the area."

Graziano added that UNIFIL "remains committed more than ever to its mission," according to a UNIFIL statement late Sunday.

Western-backed Lebanese Prime Minister Fuad Saniora condemned the "suspicious terrorist attack," saying "it targets Lebanon's security and stability"

Media reports earlier this month said interrogations by Lebanese authorities with captured al-Qaida-inspired militants revealed plots to attack the U.N. force. The warnings became more serious after fighting erupted May 20 between Fatah Islam and Lebanese troops at the Nahr el-Bared Palestinian refugee camp in the north. The militants have threatened to expand the battle to other parts of Lebanon.

In addition, al-Qaida's No. 2, Ayman al-Zawahri, in videos broadcast in September, has denounced the reinforced UNIFIL.

But the majority anti-Syrian coalition in Lebanon's parliament has accused Damascus of being behind the bombing.

"This attack falls within the framework of the same terrorist project the Syrian regime is waging against Lebanon, its stability and independence, . . . through explosions and assassination," said a statement issued late Sunday by the group.

The coalition has regularly blamed Syria for attacks in Lebanon, beginning with the assassination of Hariri in 2005, a suicide truck bombing in Beirut that caused an international uproar, forcing Damascus to pull its army out of Lebanon after nearly three decades of control.

Since then, a series of attacks against anti-Syrian figures have been blamed on Syria, including a recent car bombing that killed a prominent anti-Syrian lawmaker. Damascus has denied involvement in such attacks.

The coalition has also blamed Syria for the conflict with Fatah Islam that has killed more than 150 people.

Syria and its main Lebanon ally Hezbollah have condemned the attack. So did the United States and France.

Syrian Foreign Minister Walid al-Moallem told his Spanish counterpart in a telephone call that the attack was "a criminal act that aims at shaking security and stability in southern Lebanon," Damascus' official news agency reported Sunday.

Syria has warm relations with Spain despite its tense ties to other European countries and the United States. Moallem visited Madrid in recent weeks.

The Shiite Muslim Hezbollah called the attack a "suspicious act that harms the people of the south and of Lebanon." The militant group has had good relations with UNIFIL.