Lebanon has accused 12 people of planning bombings and the assassination of prominent figures across the country's confessional divide, a judicial source said on Thursday.

At the same time, a colonel who defected from the Syrian army has been arrested and charged with recruiting Lebanese to fight against the regime in neighbouring Syria.

The news comes a day after the arrest was announced of two Syrians and a Lebanese for "belonging to a terrorist network" that was planning bombings and assassinations.

On Thursday, military court Judge Sakr Sakr accused a dozen people, including the three in custody, of "planning to assassinate people in the north of Lebanon and to set off car bombs in various regions... where many religious communities coexist," the source said.

The accused "had bought guns, detonators, rockets, bombs and ammunition," he added.

The source did not say who was thought to be behind them or what their targets were to have been.

But daily newspaper Al-Akhbar, which is close to the powerful Shiite movement and Syrian regime ally Hezbollah, said at least two assassination targets were unnamed figures close to it.

The newspaper also said there was a plan to blow up a bus carrying Syrian refugees in the north.

Independent daily Al-Anwar said the cell had "constructed 12 bombs to be set off in the main cities" of Lebanon, and also planned to murder figures from across the political divide, as well Syrian opposition figures in the country.

Lebanon has become increasingly affected by the Syrian civil war, and has already been rocked by a number of deadly bombings.

Supporters and opponents of Syrian President Bashar al-Assad have engaged in sporadic clashes, some of them deadly, in the northern port city of Tripoli.

Much of Lebanon's Sunni community backs the Sunni-dominated uprising against Syria's government, but Lebanese Shiites, including Hezbollah, largely back the Syrian regime.

The latest charges come after a string of car bombings, including two in the southern suburbs of Beirut and one in Tripoli.

The August 23 attack in Tripoli, a twin car bombing, killed 45 people and was the deadliest such attack in Lebanon since its 1975-1990 civil war.

The attacks in Beirut, which targeted neighbourhoods that are considered Hezbollah strongholds, killed 27 people.

Meanwhile, a judicial source said police had arrested former Syrian army colonel Ahmed Amer in Tripoli as he sought to recruit potential rebels.

He was seized at an unspecified date "when he arrived from Istanbul, where he had met leaders of the Syrian opposition," the source said.

"A CD and a USB memory stick in his possession... contained maps of military installations" in Syria, the source added.