The minister, Elias al-Murr, was driving himself from his home in an upscale Christian suburb 10km north of the capital when an estimated 30kg of TNT exploded in a nearby parked car.
Seven cars were destroyed by the blast, which left a scene of devastation that has become all too familiar for Beirut residents.
Director of Aljazeera's office in Lebanon, Ghassan bin Jiddo, reporting from the scene, said the explosion was so fierce the area had been badly damaged and blackened.
At the scene
He said al-Murr, who is also deputy prime minister, had been injured in the face and had been transferred to a nearby hospital.
"I saw Minister al-Murr, walking out of his car. He was injured. There was blood on his face. His clothes were torn," an eyewitness told Aljazeera.
"Minister al-Murr asked me to get him a car. We borrowed a lady's car, four minutes after I saw him. We then transferred him to the hospital."
"He took his two companions with him to the hospital," the eyewitness added.
A Lebanese military judge had arrived at the scene, added Bin Jiddo.
A military judge investigated the
site, which was badly damaged
Television pictures showed victims covered in blood, with one being helped out of a car on to a stretcher by rescue workers.
The pictures also showed the burning shells of two cars.
The images clearly indicated that the explosion was due to a car bomb, the correspondent reported.
The house nearby of the Mexican ambassador to Lebanon was damaged and his wife wounded in the blast.
Al- Murr, the son-in-law of President Emile Lahoud, was taken to Serhal hospital, where he issued a statement aimed at "reassuring the Lebanese".
"Thank God I am in good health and I wish a speedy recovery for all the bodyguards and the wounded. We must support them as the country is going through a very difficult period," he said from his hospital bed.
Nine people were hospitalised, some of them with serious injuries.
The attack is the latest in a series targeting politicians and journalists since the assassination of former prime minister Rafiq al-Hariri on 14 February this year.
"Al-Murr is President Lahoud's son-in-law. Therefore, this attack is a very harsh message"
Abd al-Rahim Murad,
Ex-Lebanese defence minister
Abd al-Rahim Murad, a former Lebanese defence minister, said he believed the objective behind such operations was to cause disorder in the country.
"Such attacks aim to damage the security and economic situations in the country," he said.
"Elias al-Murr is a neutral person and a prominent figure of the Lebanese national work," he said.
Murad accused what he described as "foreign Western sides" of inciting the forces attempting to cause chaos in the country.
"It is very natural to point the accusation finger at the Zionist enemy that seeks to cause chaos and trigger enmity between us, particularly following the elections that were carried out in Lebanon.
"We hope the government will soon be formed so it would help to maintain security in the country and halt this disorder which has been taking place during the last three months," he added.
"Al-Murr is President Lahoud's son-in-law," Murad said. "Therefore, this attack is a very harsh message.
"We hope the current security authorities will be able to learn who is behind the explosion.
"We, members of the former government, used to be accused of not being able to maintain security," he said.
"Now, we have the right to question the role of the current security. Why are they not able to maintain security and learn the sides behind these explosions?" he added.
Aim of attack
Jumblatt linked the attack to the
probe into al-Hariri's killing
Druze leader Walid Jumblatt claimed the attack was aimed at silencing a man who could potentially give incriminating evidence to international investigators still probing the Rafiq al-Hariri murder.
"There is a plot to eliminate all the witnesses or everyone able
to give information on the assassination of Rafiq al-Hariri," Jumblatt told private satellite channel LBCI.
Rafiq al-Hariri's son, Saad, who heads the Future Movement bloc that won recent parliamentary elections, spoke of a "hand that wants to destabilise Lebanon and kill politicians and journalists".
Interior Minister Hassen Sabeh described the attack as a message aimed "at destabilising Lebanon and forcing fear, desperation and instability on its people".