Against a backdrop of political crisis since the February 14 assassination of former premier Rafiq Hariri, the bombers carried out a fourth strike on a Christian area in less than two weeks.

The latest attack came at night-time in an underground parking lot of a shopping and residential complex in the mountain resort of Brumana, an opposition stronghold 20 kilometres east of Beirut.

About a dozen cars were destroyed in the blast, which caused heavy material damage, television pictures showed. The eight-storey centre contains a branch of the Mediterranean Bank, owned by the Hariri family.

Leading opposition figure Walid Jumblatt blamed the Syrian-backed Lebanese security services for the explosion, in an interview with the Arab satellite station Al-Jazeera.

“They know that their days are numbered, therefore they are trying to terrorize the people,” the Druze MP said.

“What is requested is that an international commission be created and that the (heads of the security and intelligence) services be sacked so that we can have clean Lebanese services,” he said.

He was referring to a planned UN commission of inquiry into the assassination of Hariri, which Christian, Sunni and Druze opposition figures blame on the Lebanese authorities and their backers in Damascus.

Beirut has been on edge since 11 people were wounded when a bomb exploded beneath a car in Jdeide March 19, an attack that was followed by a blast in Kaslik north of Beirut on March 23 that killed three.

At least two of the dead were Indian nationals, in the only fatal attack among the series of bombings which have been carried out at night in quiet areas in a clear bid to minimize casualties.

On the political front, pro-Syrian Lebanese politicians earlier Friday rejected Mr Karameh’s decision to step down after having failed to persuade the opposition to form a national unity government.

“We asked him to continue to form a government,” said parliament speaker Nabih Berri.

A government must be formed before parliamentary polls, due by the end of May, can go ahead.

Mr Karameh was to have stepped down at a meeting Wednesday with President Emile Lahoud but he delayed the move pending consultations with his allies, who have been under stiff pressure since the murder of his rival Hariri.

Mr Karameh resigned a first time on February 28 under the weight of huge demonstrations triggered by Hariri’s murder as well as pressure from the international community and the anti-Syrian opposition.

President Emile Lahoud re-appointed him 10 days later.

The opposition on Thursday accused the outgoing government of foot-dragging to delay the elections in a bid to retain control of parliament.

Amid the political deadlock, the Syrian army has been dismantling positions in the Bekaa Valley of eastern Lebanon as it accelerates a troop pullout launched last month that will end a 29-year deployment.

Syrian Foreign Minister Faruq al-Shara in a letter to UN chief Kofi Annan on Tuesday pledged that his country would pull out its remaining troops, estimated to number some 8,000, before the elections.