BEIRUT -- A powerful car bomb tore through a business district in the centre of the Lebanese capital Beirut on Friday, setting cars ablaze and killing a prominent pro-western politician and four other people.

The bomb targeted Mohammed Chatah, a former finance minister and a senior aide to former prime minister Saad Hariri, security officials said.

The National News Agency confirmed Chatah and his driver were killed, along with three other people. The Health Ministry said more than 70 others were wounded.

Lebanon has seen a wave of bombings over the past months as tensions rise over Syria's civil war.

Hariri heads the main, western-backed coalition in Lebanon, which is engaged in bitter feuding with the militant Hezbollah group, which is allied to Syrian President Bashar Assad. Several recent bombings have targeted senior Hezbollah figures or districts where the Shiite group dominates.

The Friday morning blast was heard across the city and sent thick black smoke billowing in the post downtown commercial district behind the government headquarters and above the seafront of the Lebanese capital.

The army cordoned off the area to prevent people from getting close to the scene, where the twisted wreckage of several cars was still smouldering. The NNA said the explosion was the result of a car bomb, but security officials said they had no immediate confirmation.

The security officials said Chatah was on the way to a meeting at Hariri's downtown residence when the bomb hit. They spoke on condition of anonymity because they were not authorized to talk to the press.

Footage broadcast on Lebanese TV showed medical workers rushing the wounded to ambulances. At least two bodies could be seen lying on the pavement.

The Syrian war has raised tensions in Lebanon's Sunni and Shiite communities as each side lines up in support of their brethren in the conflict next door.

That has fuelled predictions that Lebanon, still recovering from its 15-year civil war that ended in 1990, is on the brink of descending into full-blown sectarian violence.

Chatah, a prominent economist and former ambassador to the U.S., was one of the closest aides to former prime minister Rafik Hariri, who was killed in a truck bombing in Beirut in 2005, not far from Friday's explosion.

He later became finance minister when Hariri's son, Saad, took over the premiership, and stayed on as his senior adviser after he lost the post in early 2011.